dackass
A person who thinks they're smart, but they just don't know how to shut up.
He called me a dackass for not knowing the answer, but he talked for 10 minutes about his dog's hair.
She said I was a dackass for not knowing the movie, but she listed 100 songs and none were the right one.
He called me a dackass for not knowing the game, but he explained it for an hour and I still didn't get it.