Sometimes, in Sleeping Dogs, you kick so many arses that your still-standing foes give up and run away. This usually happens when you're clearing out the "drug bust" zones, which begin with a fight and end with some sweet, delicious camera-hacking.
For some reason, after you've kicked all the asses, the fleeing guys kinda… lose their minds a little bit. They hop onto the bikes and cars they arrived in and sort of drunkenly careen around all willy-nilly before eventually swerving out onto the street. It's a funny bit of fiction-breaking bugginess. A particularly good one has been captured here by GameFails.
Don't tell anyone, but when the punks run away, I like to chase 'em down anyway and throw them into a dumpster or something.