Something very awesome, contrary to what most would believe.
Person 1: Dude so their restrooms didn't have any toilet paper in the cubicals...
Person 2: Damn man, what did you do?
Person 1: I shat in the hand wash basin of course.
Person 2: Mad gay.
When something is so gay as to totally redefine one's perception on life, society and the universe. When something is Mad Gay, it is so far beyond gay that it necessitates a new definition - this is mad gay.
Person #1. "Hey dude I was going through your cd collection the other day.."
Person #2. "Oh?"
Person #1. "Yeah. I found your secret stash. You know. The Britany. The Christina. The Aqua."
Person #2. "Oh..."
Person #3. "That's Mad Gay."
adj. extremely uncool (gay)
antonym for wicked or awesome
Ming: have you talked to that guy Alon? he seems over-confident.
Derrick: yeah. that guy is mad gay. lol