Mr. Lacoste is a French waiter.
He served at Freddy Quimby's birthday. Freddy was unhappy with his pronunciation of the word "chowder" and chased him into the kitchen, where he supposedly beat him up. Freddy was arrested for this, but Bart Simpson saw what really happened. Later, in court, Bart explained what really happened. After Freddy had left the kitchen, Mr. Lacoste slipped on a Rice Krispy square and then went through a series of accidents which left him badly injured. After this, Mr. Lacoste stands up and claims he is not a clumsy waiter but as he does this he trips over a chair and falls out a window into a truck of mousetraps, proving that he is clumsy.