Sadly im gonna guess hes 23. Thats just the number thats in my head. But him and his ex both act like children and are never going.to grow up
Don't do anything. Why risk getting yourself into a cycle of bullshit pranks that you each play on each other. Be the more mature person and don't be a spiteful little cunt like half the human population. She'll get hers in some other form at a later time.