
Revealing mistake: When the crocodile attacks Sue from the water, it holds on to her canteen for two shots. You can see that the animal actually holds on to a prepared version of the canteen - it is cut in half, with its lower teeth inside to hold it more "comfortably" during the pull.
Answer: It is a party thrown by one of Sue's socialite friends, presumably the husky-voiced woman whose crotch Mick grabs. The party is not "full of hookers", Simone is there as the hired escort of the old man she is dancing with, who Mick naively believes to be her father. We can assume the old man paid for Simone to be his date to the party and likely for some time alone with her afterwards. There is no stated reason for why the party is being thrown.
BaconIsMyBFF