assin' it up
Acting in a manner consistent with an ass (either a jackass or just an ass ass). Braying arrogantly and assishly. Producing excrement when one acts or speaks. See Donald Trump.
"I see Trump was on Twitter again in the wee hours, assin' it up!"
assin up the place
stinky, filthy lazy and of general poor hygiene who's room smells like feet and ass.
That dude just lays around all day assin up the place.