its like relaxing without doing nothing..as far as ı guess

"Chilling" means the same thing as the expression "hanging out". It's just resting and not doing a whole lot.

Actually, Idan has a point - maybe "are you chilling me?" is a derivative from "to give someone the cold shoulder". However, I doubt many native speakers would be familiar with this usage. Our first thought is "to chill" = to relax.

"are u chilling me?" doesn't make any sense to me after all....

could also be a synonym for "deterrent" or "daunting", which means "abschreckend" in german. German inhabitants also use "chillen" as a word for "relax". Depends who said that to you. A lot of Germans don't know, that this word has a differnet meaning in english.