ah, birthday party with clowns... the only occasion in my life when i wished to carry "little boy" (how appropriatly named, btw) in my purse so i could swing it at clown's head and take all the party to a "better place". my only consolation was the fact i was seated next to friend's father (RIP) who was blind, part deaf (the other part went too, with the party's music) and almost entirely mute.
in any case, make sure children at the party speak spanish because clowns would only use that. they normally carry with them CD's with children's songs and appropriate equipment. also, warn the adults they'd have to be involved. apparently the best part of the program are competitions that make parents look like complete fools. and prepare awards: colour books, crayons, sweets.