Cool is someone who does or acts very original, and you think that it is amazing how he/she is so original, yet the idea is so good, that you want to do it as well.
Cool was hard to explain.
[EDIT:] Now that I read more of the posts, I see that people are saying what they think is funny and cool.
I think some people are funny, along with Seasons 1-10 part 1 of South Park (and Make Love, Not Warcraft, that was just great). The Simpsons, earlier Malcolm in the Middle's. Honestly, that show was sooooooo funny, I think it was the best show ever, all the way until the season after the beauty pageant, now they just suck.
I think certain people are cool... And that's all. Badasses are cool too, but badasses are people too, and badass is basicly just another word for cool so that's kinda redundant.