What are good ways to annoy a 12 year old?

I work at a community pool, and we have one specific boy who makes everyone’s life a living hell. He comes in everyday after school, because his mother likes to think of us as a babysitting service, and doesn’t shut his trap from the time he gets there until the time he leaves. He constantly provokes us to get into an argument with him, and I’m tired of it. Just the other day, another guard told him to get out of the pool and escorted him to the locker rooms. He later told his mom that the guard was trying to watch him undress. A blatant lie! Does anyone have any ways to teach him a lesson, but still be discreet and not harmful?