Means 'pee right back' taken from the shorthand brb where the first b is replaced with a p.
10π 15π
Oh my god did you see how Tracy look last night? Yeah she looked like a PRB!!!!
If I come over is that ok?
Yeah my parents are home but that wonβt be a prb
Pee right back; for when you want to say brb but give a reasonable eta
"Prb"
"Make sure you shake it dry"