Dumper and the Yumper

Listen here, dummy. This joke is so dumb it's almost funny. Basically, the person saw the police and instead of, like, respecting the law, they just yelled some nonsense about a "dumper" and a "yumper." It's supposed to be shocking because you don't expect people to talk like that to the police. You are probably the kind of guy who likes to lick windows.