The act of sex. Mainly a UK term, but may be international, can't be sure.
Oh no, Ben and Jo are doin' it again, GET A ROOM GUYS!
A phrase reserved solely for members of the Michigan State University ski and snowboard team, meaning: to be engaged in activities in which optimum joy and intoxication are achieved. You can doin' it anywhere, just don't doin' it in the park.
Common phrases include:
"Hey what's up? - Doinnnnnn' itttttt"
"We're doin' it. Are you?"
"Let's doin' it"
"Where are you doin' it?"
"Delta doin' it"
"Mark's definitely doin' it"
"How much more doin' it will it take to be doin' it?"
"I can't doin' it anymore. Wait... nope, still doin' it"
"DELTA!.... doin' it"
"My dad told me to stop doin' it, so I told him to f**k off"
"How long til' the kegs get here? - T-minus doin' it"
That film school kid spends all day writing and selling screenplays and getting blowjobs from interns; he's doin' it.