One person starts counting and it moves around the group. Everytime it gets to a multiple of 5 (eg 35) that player must say 'fizz' instead of the number, then it carries on. Everytime it gets to a number with 7 in it (eg 17, 27, 72) that player must say 'buzz' instead of the number. If any number falls into both categories then the palyer must say 'fizzbuzz'.
Heres an example:
Any person who gets it wrong in any way (they forget to say fizz or buzz or they say the missed out number) has to drink a designated amount of alcohol. The more you drink, the harder it gets!