The quickly whispered phrase a gay man says to his young lover as he's getting ready to plunge his penis into their butthole. It can sometimes also be uttered when there is a fecal accident as a result of said buttsex.
"Dontbescarried, Tyrone. It'll only hurt at first."
"There's shit all over your mom's futon, but dontbescarried, we'll blame it on the dog."