I'm planning to trip the employee purposely and spill the tray of food.
Why would you need to be so mean to the employee?
I think it will be funny.
Tripping somebody like that on purpose is mean. The employee will have to clean up the mess and you might be refused service there if you do that.
I don't care. They could have hurt somebody else.
They more than likely would not have hurt someone else. You were the one that tripped them, which was cruel by the way.