Have been lurking around Michelle Ward's site over the last couple of weeks and thought I'd take part in this crusade. Can't provide link so here's the long version - http://michelleward.typepad.com/how_cool_is_that/
Sayings used in our house...
'Hello McFly' from Back to the Future Movies - used in our house when someone does something particulary stupid or states the bleedin' obvious.
'Lunch at 12' used by my sis and I to point out that there is an incredibly good looking guy around without being obivous.
'Smile' code word for 'please check my teeth and tell me if anything is stuck in them'. Well used by sis and I.
'My imaginery friend, Petri, did it' - oft used saying by DS (4) whenever I notice something is broken, ruined, not where it should be etc... I'm sure will become the much stated answer 'Petri did it' whenever someone asks 'who did this!'