Simple combination of
Butt, and anus. Cute way of saying "your an
asshole", but to a loved one like a
bf or
gf.
Gf: "Honey did you remember that it's my
birthday today?" Bf : "oh what? really?"
Gf: "how could you forget?" Bf: "im joking baby," *pulls out flowers* Gf: "your such a bnanus"