Best definition
You Da Man. This implies that you are congratulating your fellow with a sincere generic compliment.

-Yo man, I hooked up with some-hot-girl last night!

ydm: define #2
You disgust me. Simple phrase, mostly aimed at parents that make horribly decisions they think are necessary, or people that think they know wat they’re saying.
Facebook status:

You actually think that it was me when i TOLD you i wasn’t there?! wow, ydm.