Destroying federal property is illegel - if I were to cut a penny or nickel in half with a bolt cutter, that would be illegal.
If I were to break into a pay phone, or blow up a mailbox, that would be a federal crime
However I don't think having someone scribble their name on a bill is a crime. Now if you were to tear it 40 pieces, yes that would be illegal.
Cash can still be redeemed for its face value if it has writing on it
However you could run into copyright issues, or some other kind of crap. If one of these skateboards knows you are trying to sell the bill, they might object to that. However I think someone would just warn you and ask that you cease and desist. I seriously doubt someone would actually try to prosecute you unless you would informed then sold the bill anyway or something.