Having lots of background experience in a particular subject. Usually a term abused by ignorant and cocky fucktards.
As faggot ass Moy says:
"You gotta know your networking, how to hump a telephone pole, and feed a fish to a walrus... All I'm saying is that you have to wear your Third Hat... and I know you kids these days just don't have it."
"My son is a straight-A student in Notre Dame, he really flashes his third hat man."
"I think my cock is big because I'm wearing my Third Hat."
"Moy is a faggot."