1. Either referring to muscle, a muscular
man, or the
act of building muscle.
2.
A word referring to a vaginal fart. Otherwise known as a "queef".
"Tracy, whatchu doin', girl?"
"Building some mousa."
"Jenny, what was that noise?!"
"OMG, so
fucking sorry. I just had to mousa."
"Oh, I
always have to after sex, it's alright. Let your mousa out,
bb."