First you have to write out or type out a stack of cards with many different words on them. Nouns, Pronouns, Verbs, advebs, adjectives, conjunctions, everything. you'll need at least 5 words per person playing.

Randomly select teams of 4-6 people. Each team competes to try to come up with the funniest, most creative sentence they can put together with the cards they are given. Everytime they order a drink, you hand them a card. When all the word cards are handed out, have them tape their sentances on the wall. You judge them and the winning team wins a round of drinks. 

I played this at a barcrawl I ran last year and everyone had a blast, and mingled with people they wouldn't normally mingle with.