Get lost. Mexicans are hilarious. There aren't really any groups that are better to make fun of. Queers used to be good, but people get all offended these days.
Actually, the only group of people that it is acceptable to poke fun at are those who live in Appalachia. Every other group in the world has been protected by Politically Correct speech but hillbillies, moonshiners and cousin marrying people are still fair game. >:(