You will notice that there are clowns running around in this area and they will jump on you if they get close. Most of them will have chainsaws and will try to harm you and you must hit a bumper to know them off but the bumper also deals damage to you if it doesn't have the health sign on it.
There will also be a clown running around with a bomb in his hand. He doesn't show up until you run into the bulls eye that is closer to the base. A cannon will shoot the bomb guy into the area once you hit the target and he will try to jump on you also. You want him to jump on you though and when he's on your car you want to hit one of the two spinning ramps when its green and ram the clown head with the bomb guy. Be careful because the bomb guy has a time limit on him.