asshat

A close cousin of the assclown, typically identified by a jovial expression and an outward misunderstanding of how he/she is perceived, combined with a generally misguided conception of what is socially acceptable amongst his/her peers.

Said persons' frequent attempts at humor usually lead to him/her making an ass out of his/herself. (Not to be confused with asshole.)

"Quit throwing pennies at that homeless man, you asshat."

"Hey asshat, thanks for double parking."