You can not show your teeth
Get the person to laugh when you say pterodactyl to them
Get your campers in a circle. All camper must cover their teeth with their lips. Pick one person to start and they must turn to the person to their right and say pterodactyl without showing their teeth. The person they are saying it to can not show their teeth either. If either of them do they are out. And it continues on around the circle clockwise until there is one person left.
You may laugh as long as you don’t show your teeth. You may also make faces to make it more funny.