Gurney Slade
My family all read The Meaning Of Liff a while ago and (as I'm sure everyone does who has read it) came up with a few of our own.

Gurney Slade is "to distort the face of a loved one, while they are unconscious on a sofa at a party, for the amusement of others".

My mum proudly coined that one and it stuck. We rarely actually indulge in Gurney Slade, more often use it as a threat.

Ooh, and that's another thing. Gurning.
When gathered together for any kind of family event where photographs are taken to remember the occasion, the instant a camera is pointed at any group of us we are gripped by a strange compulsion. We don't pose and smile... we gurn. With no direction or communication, we simultaneously pull the same face (and sometimes each others'). There are no normal pictures of us as a family since Christmas 2005.

Some examples:
Christmas 2006 1, 2
Christmas 2007 1, 2
My brother's wedding (note how effortlessly my sister in law fits in with us).
( warmfuzzies Isn't here, Tue 25 Nov 2008, 23:36, 10 replies)

.
* clicks for the photos *
( mistaspakkaman and the inedible shifting caterpillars, Wed 26 Nov 2008, 0:36, closed)

ARGH!
They're among us! Run for the hills!
(Vice Admiral Sir Charles Cockbrush KCB MBE DSO, who is finding it increasingly difficult to log into b3ta.com wants to duck your aunt and kick your puppy, Wed 26 Nov 2008, 8:46, closed)

Will you marry me?
(Emily Bruce-Dickinson http://jovialfellow.blogspot.com/, Wed 26 Nov 2008, 9:58, closed)

hahah
that is quality!
(Halfy By light alone, Wed 26 Nov 2008, 11:00, closed)

Brilliant!
Your family are ace!
( Labia Majora You keep on talking but it makes no sense at all, Wed 26 Nov 2008, 11:04, closed)

Superb!
I occasionally buy mead from a farm shop near Gurney Slade.

Your sister in law has nice teeth.
( M3rx likes the Asian ladies, Wed 26 Nov 2008, 12:35, closed)

Hehe...
The first Christmas 2007 looks like it is called poo! Plus, you look like a much odder version of Madness in the "One Step Beyond" video!

The other 2007 one - now that is a monster of a beard!
( Agnostic Antichrist Baltimora, Wed 26 Nov 2008, 14:03, closed)

That's my stepdad.
He's Scottish. When my brother married an Albanian (in Albania) and we all went over for the wedding, he wore his kilt and full ensemble, to the bemusement of the new in-laws :)
( warmfuzzies Isn't here, Wed 26 Nov 2008, 17:48, closed)

there
also seesm to be a family nose, you all have the same shaped conk
(Halfy By light alone, Wed 26 Nov 2008, 14:42, closed)

Yes
although that's not so much a ritual as a biological function over which we have no control :p

which is prolly exactly what a ritual is
( warmfuzzies Isn't here, Wed 26 Nov 2008, 17:55, closed)