When something is so horribly bad it cannot even compete at the pro level; something that is very weak in an amatuer way. Very similar to weak sauce "Ama" from "amature". Originated in the St. Louis "Ladue Crew" slang.
You're parents were out of town and you didn't have a party? That's ama weak.
When something is so pathetic that calling it weak does not fully describe the level of weakness that has been achieved.
You've only had two beers and you're drunk? Thats ama weak.