"Okay, okay, uncle!" (said by the person getting attacked).
To cry uncle: Concede defeat, as in The Serbs want the Bosnians to cry uncle, Farlex Dictionary of Idioms
The phrase I've proposed is a bit sarcastic. It's an amusing way of showing that the person was being quite aggressive.
If you think your teasers won't be familiar with cry uncle, here's an alternative:
(Slapping both hands to clutch your chest dramatically, while falling, or almost falling, out of your chair) You got me! Man down!