Put that back. You don't know where it's been.

A fun thing to do next time you and your friends are talking about dinosaurs is to wait until someone mentions a pterodactyl and inform them that actually, the pterodactyl is a “pterosaur”, as the term dinosaur refers exclusively to land-dwelling reptiles of the superorder Dinosauria and therefore does not include pterodactyls or aquatic reptiles such as ichthyosaurs and plesiosaurs, and wait to see how far you can get through that explanation before one of your friends (or a passerby who happens to overhear your conversation) punches you in the face.