heres a few
[list]
drink every time someone comes on performs/dances/sings to a lady gaga track[/list][list]
every-time someone comes on and uses the mercy vote[/list]
feel free to suggest more...

I used to make a drinking game for all the semis and the final last year - made the show a lot more interesting

Here are a few rules I used:

Everytime Susan Boyle is mentioned

Everytime an act makes Amanda cry

Everytime an act makes the telephone gesture

Everytime You Raise Me Up/ Rule the World/ the World's Greatest are played after an act

Everytime a dance act was compared to flawless/diversity (might not happen so much this year though)

Everytime judges use bad maths (eg a million percent yes)

I think I will have to do a drinking game this year too. The standard of acts is so bad it will make watching more bearable