Originally a hybrid of bimbo and dingus, a bimbus is basically someone who is acting the fool and/or dicking around in a generally harmless way. Variations include "bimby," "bimb," and "bimbass."
A: Yo, did you see that guy try and do a skate trick at all in general as an adult?
B: Yeah man, what a bimbus.
A: Joram bleached his hair in an attempt to be punk rock.
B: Punk rock? But he just looks like a bimbus!
Joram: NOTHING IS MORE PUNK ROCK THAN BIMBUS.