A hat with ear flaps, a funky design and tassles on each side that Dappy from N Dubz wears, hence the name.
They are actually called sherpa hats.
Dude 1: Check my hat, dude.
Dude 2: Who do u think u are, Dappy?
Dude 1: Well, yes. To be honest. It's a Dappy Hat.