"Wafflebutt" is a pejoritive directed at cops in general, and motorcycle cops in particular.
This definition is based on the impression left on the gabardine pants worn by motorcyle cops from the criss-cross pattern on their bike saddles, and implies laziness based on the duration required to impress the pattern on their butts.
This definition prevailed in the '70s and before.
"Hey, wafflebutt! Get off your ass and do something!"