On Cowdays, first get the anti - South Park Rally
On Cowdays, first get the antidote; then give everyone pinkeye (it's behind the bell near the bullpen) afterwards climb the stairs in the room with the haypile in the corner.
Go to the top and pull a 180 and wait till someone gets to the top. Before they hit you, floor it off the edge and take off out the door.
For added enemy slow-downage, get taco pickups or the frog pickup and lay them on the stairway leading up.
You can also launch turds, cats, stupid beams, or peace signs at them as they come up.
Cats are the best because they stop anyone who comes too close to the enemy hit by it, also there is a Mr. Hanky Poo on one of the ledges in the same barn.
Get it to make sure noone can get you and knock away the antidote.