You Fail at...(insert verb/noun here)
You use this to tell people they are horrible or can't do a certain thing.
It can be used as a joke to some, but also to make people really mad by a major insult.
Mostly it is used as a joke though.
Bob-"hey man, i fell off of the stairs"
Jim-"you fail at walking down stairs"
Bob-"dude, my girl just broke up with me"
Jim-"you fail at life"
Bob-"dude i hate you"