There's no one who can roast you better than your parents.
They know all of your deepest, darkest secrets. They wiped your butt when you were a kid, they've amassed a lifetime of roasting material on you and should they choose to act on any of it, they could end you in a heartbeat.
Most of the times, parents are way to benevolent to embarrass their children beyond belief. But when they're not so kind, amazing things happen. Well, it's amazing for everyone except their humiliated kids.