I'm just going to edit the question slightly...
The things I've been most ashamed of doing with I would do if I had a penis (Aka: Things i would do if I was a man for an undisclosed period of time).

1. Pee Standing Up
Whilst I am aware women can pee standing up with a bit of jiggling and faffery it's no where near as convienient as whipping out your member and letting that stream gush out over the fence/bush/next doors cat. In fact if I could pee standing up I'd go and see a U2 gig so I could piss in bottles and throw those golden bottles of love at Bono. Hopefully he would scream "I'm melting!" and disolve into a small untalented smudge on the stage.

2. Have incredibly quick Sex
Yup I'd find myself some hot chick and throw her down on the bed, stripping off and I plow deep inside of her. I wouldn't bother thinking about sandwiches or the latest debate in the House of Lords, I'd think about hot sweaty sex and I'm pretty sure I could blow my load within a few minutes leaving her disappointed and frustrated whilst I rolled over and went to sleep. In the morning I'd probably wake up and laugh at her as she flicked the bean trying to build herself up to orgasm. I'd probably then go and piss in her sink just because I could.

3 Experiment with substitute mimsies
Sticking my finger in a carefully heated watermelon probably doesn't have the same thrill as thrusting my rock hard dick into one.

4 Take Pictures of it and send it to everyone on Internet dating sites
As a man I would assume everyone posting on internet sites would want to see pictures of my awesome chunk of man meat. I'd probably take a few pictures though looking for the one that makes it look like I'm a caring kind of guy who wouldn't piss in your sink.

5. Scratch my balls in public. All the time
Not for any reason than to gross people out when they see my hand down my pants and hear that nice scratchy sound as I give my pubes a good rustling

6. Delight that my penis doesn't start dripping blood once a month
That sounds like I'd have to start showering more than twice a week, or at least change my boxers.

7. Ignore decent suggestions and just think about my cock all day
I'd pretend I was being a sweet caring guy who was open to compromise when I changed the wording of my latest fantasical idea to try and include all those whining women sorts who were jealous they didn't have the same gigantic bulge in their trousers as I did. But they are probably all on their periods or something.
( TGB checking Off Topic is still shit at, Fri 13 Mar 2009, 11:07, 13 replies)

I think
That you were a dude in a past life.
(powervator and NONE SHALL PASS, Fri 13 Mar 2009, 11:09, closed)

Woo!
Go Grammer badger, go Grammer badger, go.
( girlinthehole, Fri 13 Mar 2009, 11:09, closed)

Don't forget when peeing standing up
To miss the toilet occasionally.
( The Light in Chains don't touch the Pope's boner, Fri 13 Mar 2009, 11:24, closed)

^
'Occasionally'?
(powervator and NONE SHALL PASS, Fri 13 Mar 2009, 11:30, closed)

Guys
She's on to us!
(kitescreech still here, Fri 13 Mar 2009, 11:25, closed)

I think you may be right.
But I can see a sink from here, so there's something I must do if you'll excuse me...
(robbersdog, Fri 13 Mar 2009, 11:47, closed)

it's all fun and games until you manage to get kicked (or similar) in the balls.

( theoriginalsteve <this space intentionally left blank>, Fri 13 Mar 2009, 11:50, closed)

Yup
That's pretty much how I employ mine..
(Vic Flange, Fri 13 Mar 2009, 12:20, closed)

.
"I'd probably then go and piss in her sink just because I could."

A woman after my own heart!

"I could blow my load within a few minutes"

A few? I'd call that considerate!

Pretend you're doing her up the botty and you could probably manage sub-30 seconds.
( 100% Cock Raw like carrots., Fri 13 Mar 2009, 12:34, closed)

click for pissing on Bono
Having a penis Is a big responsibility, You have to be the one who fills the bottles full of piss before ANY gig.
( willenium Fist bump for verification, Fri 13 Mar 2009, 13:09, closed)

Part of this
sounds like penis envy, part of it unhappy experiences!

Typical women, not knowing what she really wants! (joke)
( DavyBoyInGravyJoy Grey Goose Vodka on Ice, nothing finer, Fri 13 Mar 2009, 13:57, closed)

YAY
I applaud you! I'd do exactly the same if I had one for a while..
(sneezymonkey, Fri 13 Mar 2009, 19:51, closed)

Sort of Penis envy...
Mainly due to point 6 :p
( TGB checking Off Topic is still shit at, Sat 14 Mar 2009, 9:29, closed)