Doin (DYM 20)

Listen up, buttercup. "Doin (DYM 20)" is like saying you're knockin' boots, but you're using some kinda acronym only a dummy would need explained. And considering you're asking me, Explain Bear, to break it down, well, let's just say you ain't winnin' any smarty-pants contests. So basically, Peter Griffin is saying he's doin' the nasty!