some years ago
some feminist types had daubed 'women are angry' on the side of a shop on my bus route into town. Then some wag several weeks later added 'men are a bit cross too'.
(dogspoo, Fri 4 May 2007, 14:50, Reply)

Aberdeen Uni
Engineering dept bogs. In the stall there was a massive political argument between 2 people that almost went from the top to the bottom of the wall about the state of the middle east. There must have been around 10 comments from the 2 people arguing. It still makes me wonder how long before they just went in there to argue, rather than use the facilities.
( Slippery Mick ‏, Fri 4 May 2007, 14:48, Reply)

Bottom of a toilet door...
Something clearly written then crossed out... and then the same pen starts...

"As I bent down to write here, I farted and blew liquid shit all over the toilet seat.
Please don't let this knowledge detract from your joyous use of this loo."
( Humpty Dumpty was Pushed Is unaware of having any limits., Fri 4 May 2007, 14:45, Reply)

There's always a few At uni
Our uni had a Christian Vegetarian Activists club who put lovely posters depicting slaughtered cows and pigs declaring

"There's room for all of god's animals on this planet..."

in an attempt to make people "think" but the space they'd left allowed them all to sport that addition...

"... right next to the peas and chips"
( Humpty Dumpty was Pushed Is unaware of having any limits., Fri 4 May 2007, 14:42, Reply)

more toilet prose
sat on teh lav, I was delighted/disturbed to read,

'admit it, when you have to push it out, it feels so good'


:-(
unwoo and unyay
(UnstableDan Bah, Humbug! ooooh, humbugs, nyom!, Fri 4 May 2007, 14:40, Reply)

Wall of Whitehead train station,
perfectly placed so to be visible from the train when pulled in was the slogan:

Thumbs up for date rape! :)

It took me 10 minutes to stop laughing.
(SurferRosa causing the lamentation of the womenfolk since, Fri 4 May 2007, 14:40, Reply)

On a poster in a maternity ward featuring a picture
of a newborn child was the advice "The first 2 minutes of life can be the most dangerous".

Some wag had added "the last 2 can be pretty dodgy too"
(Redbull_(UK) pfffft, Fri 4 May 2007, 14:38, Reply)

Back in the 80's...
... someone simply scrawled Up yours Mrs T on the side of a footbridge in Salisbury. Truly radical political thinking for True Blue Tory South Wiltshire.
(lolwhites, Fri 4 May 2007, 14:36, Reply)

Years ago in my dad's launderette
"I woz ere
buzzin like a bee
suckin on a sweet
called xtc"

also

"I sat here
broken hearted
dying for a shit
but only farted"

Classy
(therocker, Fri 4 May 2007, 14:34, Reply)

Aston, Birmingham
The wall of an end terrace house was painted black and had a grassy patch next to it. Thus it was painted with the usual stuff; football goals and cricket stumps in white.

Slightly more bizarrely it also had painted on it in white in huge letters;

BODie + DOiL

probably by an ill educated fan of the Professionals.
( abefroman skating on the thin life of modern life on, Fri 4 May 2007, 14:32, Reply)

Not quite rude...
My sister in law wanted to be rude with her older sister and brother and decided to write the rudest word on their house wall in chalk which turned out to be 'Sex'!

But they all chickened out and ended up writing 'socks' instead, and 20 years later its still there in 4 inch high letters.
( Donkey Gums @mattcomedy, Fri 4 May 2007, 14:29, Reply)

stinky New Hampshire (USA) beer and cigarette bar bathroom wall
"For A Great Lay, Call Steven at xxx-xxx

...if children answer, ask for Daddy"
( salamander, Fri 4 May 2007, 14:29, Reply)

I love graffiti
See on a bridge in Merthyr Tydfil:
'Up to £50,000 go fish!'

?!?!?!

Seen on a six-section bridge in Troedyrhiw, South Wales - presumbaly the only rude six letter word they could think of:
'TAMPAX'

Seen at a bus stop on City Road, London:
'Tony is a junction creamer'

Answers on a postcard, please.

And finally, seen at Highbury & Islington tube:
'Jon Bowen fists pigs'
(The Moai, Fri 4 May 2007, 14:28, Reply)

on the tube:
"please give up this seat for old or disabled people"

someone scratched out some letters to change it to

"please eat old or disabled people"

it did make me chuckle. (spits falsies and wheelchair out).
(bobbysands, Fri 4 May 2007, 14:28, Reply)

Liverpool wit
More spotted in Liverpool:

"Hitler was an emo kid." with a little drawing of him with his fringe. Which made me laugh.

On the nasty-things-on-churches theme, some wag had written "Wog Jesus" on the door of a church just near the university.

And about 15 years ago, on a big switch box just outside the tunnel some delicate vegetarian had come over all unnecessary and written something like "You see meat, I see murder on your plate", under which someone had added "Nice with gravy". Have some of that, herbivore poofter!
(Crayola Oblongata Is it Monday?, Fri 4 May 2007, 14:26, Reply)

Also,
above a urinal: 'Don't look here, the joke's in your hand'.
(THIRTY-TWO - Sputnik -, Fri 4 May 2007, 14:25, Reply)

Sheffield Student Life
Not technically graffiti, but...
My best mate went to Sheffield University. They have a student radio station called SURE FM. In the window of their offices in the SU they put up A4 sheets of paper with a letter printed on each to spell out SURE then underneath they had their frequency just before starting an RSL.

The offices next door were inhabited by the LGB society. There soon appeared, again in large letters in their window "NOT SURE" which raised a smile.
(Dionysian Aut viam inveniam aut faciam, Fri 4 May 2007, 14:25, Reply)

Yet another bathroom wall
In Yellowstone National Park (think Yogi and grizzly bears), scrawled in the shitter stall:

"Remember, only bears grunt"
( HairyTwatter certified eel and sodium salesman, Fri 4 May 2007, 14:25, Reply)

On a wall near my house
are the simple words 'Life's a fuck'.

I found that to be truly profound.
(THIRTY-TWO - Sputnik -, Fri 4 May 2007, 14:24, Reply)

Bathroom wall:
Here I sit
My cheeks a-flexin'
Just gave birth
To another Texan
( setimret likes his metaphors mixed, not stirred, Fri 4 May 2007, 14:23, Reply)

Reading
The sign for the University of Reading used to quite regularly have "... and Writing" added to it.

Also in Reading, there was a curved wall on a roundabout going to a business park on which was sprayed in huge letters "FAT NOBODIES IN COMPANY CARS"
( shavedchimp something something oranges something, Fri 4 May 2007, 14:22, Reply)

On the way to Aberystwyth...
Next to one of the mountain roads there's a rock with "Elvis Lives" on it. :D
(Beans goes up to eleven, Fri 4 May 2007, 14:17, Reply)

Dean Lewtas...
...is a grass. I don't know him personally, but the huge number of times this appeared in Salford should surely be testament to his sell-out ability
(finchywinchy, Fri 4 May 2007, 14:16, Reply)

Skool Daze
When I was at school (and all this were nowt but fields) we had those nice big roller blackboards as referred to several posts down from here.

My English teacher looked like a witch and you didn't want to get on the wrong side of her. One lunchtime I snuck into the classroom and wrote something on the board in large, decorated lettering and rolled it to the back of the board.

After lunch we all sit down and Teacher (who's initials were SS and the moniker was appropriate) began. When she needed more space she rolled the board around and was greeted with an arrow pointing at her desk and the words "CAVE CANEM".

She knew who had done it, but couldn't do anything about it because at least I'd shown some of her teachings had sunk in!
(Dionysian Aut viam inveniam aut faciam, Fri 4 May 2007, 14:15, Reply)

Road sign in country road:
'CATS EYES REMOVED'

And scrawled beneath:

'£5 a pair'
(menashem, Fri 4 May 2007, 14:08, Reply)

Manchester Met Uni
Back in my uni days I used to have maths lectures in the john dalton building (I think it was that one) I always sat in the same place and one day I was confronted by a rather large picture of a Kalashnikov rifle with the slogan 'FREE KASHMIR' drawn on the desk. I thoughtfully added 'CARDIGANS FOR LITTLE OLD LADIES. The following lecture showed additions made by the same person (I assume) who obviously didn't share my sense of humour. There was a little graffiti battle going on for a couple of weeks as a result.

FREE KASHMIR FOR LITTLE OLD LADIES - I stil chuckle now
( SpikeyPickle wishes he was mabazaritchie, Fri 4 May 2007, 14:07, Reply)

Cash Manchine in Manchester
On the cash machine down the road from Piccadilly train station, written on the on the front of the machine 'BUM ME'. Always makes me look over my shoulder.
(HungOver, Fri 4 May 2007, 14:06, Reply)

One from my childhood
On the back wall of a CO-OP in Portsmouth, which was on my way to School, someone had daubed Tories are Best, which later was adapted to read Tories are Bestial. Rather prophetic I thought
(ape_hots, Fri 4 May 2007, 14:05, Reply)

Yay!
On Lancaster Place, which is on the north side of Waterloo Bridge in London, there is a building with ornate stone carvings around the doorways. These carvings include a perfect flat circle at very convenient drawing height, into which someone has drawn the most effective smiley face that I've ever seen. It's now fading with time, or because some fascist has cleaned it, but it still never fails to cheer me up when I see it.

Oh ETA! One of my less dead-eye male relatives once stumbled out to the toilet in the middle of the night for a piss and lifted the lid to find that his Mum had written "Aim Straight!" on it in magic marker. Whether he managed to or not, history does not relate.
(flimflam_machine, Fri 4 May 2007, 14:02, Reply)