You recieve a call from Otis telling you that there is a ride in the Wonderland area that is out of control, so you go to check it out of course.
When you examine the ride it goes to a cutscene and you are left to deal with a very evil clown holding two chainsaws.
It took me a while to kill him but after the 2nd time I realised that the balloons that he inflates have a gas in them, paralyzing you for a short time.
But if you have a handgun and shoot the balloons as he inflates them the gas paralyzes him, which allows you to kick some ass.
Repeat this a few times with a sword or katana and he shall be dead in no time.
You get his gnarly chainsaws when he dies too.