To have rough sex with a girl and have alot of stamina in doing so. Referencing "robocop" from the movie, this would suggest that the person in question is a "machine" in bed by "cranking dat robocop".
Even though robocop's manhood is constantly called into question, the saying rolls off the tongue quite nicely and sounds pretty kick-ass
"Then watch me crank dat robocop" - Souljah boy: Crank dat
I fully cranked dat robocop on this bitch last night, she couldn't walk straight the next day