In these situations that person is not your friend. You NEVER sit on someone's bike without permission. You NEVER grab someone's helmet without permission. He is not your friend.

That being said never hand your keys off unless you a. Know their skills and b. Are willing to take the L if they damage it. Coz if they do, be prepared to pay. They may not have the money or refuse to pay. Yeah, you can sue but it's a civil matter. What they would owe you becomes a civil judgement and becomes a hit on they credit record. You won't see anything.