What a horny stud claims to be when asking a chick to let him "do it bareback" with her.
No normal dude is 100% thrustworthy --- he may THINK dat he can control whether or not he ejaculates, but it is still an involuntary thing, and if he gets excited enough, all bets are off!
To take something small, that doesn't quite qualify as a theft. Probably from the Danish "skæv" or the Dutch "scheef", both of which are pronounced similarly, meaning "askew, or not quite right'. To change an item's ownership without permission, but only something small and of little worth.
"I skeefed an apple off the neighbor's tree." "I skeefed some chips outta your bag when you looked away." "Don't skeef my chair when I go to the bathroom."