What can you do to a gay boy at camp?

Almost exactly the same sort of things you can do to a straight boy.

And you can expect the same consequences. There IS a side consequence to camp: you might encounter the person many years later. You might have forgotten; he might not have.

Practically speaking, the notion of giving serious consideration to not shafting over people works best for the long term.

There IS life after camp.

Pranks are sometimes fun to play on people, but pulling a prank in a malicious way or because someone is different from you is not right and you will face consequences for your actions. You can be his friend, then you two can play friendly pranks on each other. Being gay is hard enough, just think how he feels. He probably gets made fun of and bullied because of his sexuality and it probably hurts his feelings and self-esteem. Self-esteem issues are extremely hard to overcome, why would you want anyone to go through that? Gay people are just like everyone else, except in terms of their sexual orientatin. Notice I said people, because they are humans to. That means they have feelings just like you, and it's not nice to hurt their feelings based on your prejudices. Think of the Golden Rule: "treat others as you would like to be treated." Would you want someone picking on you because of your sexual orientation? It would make you feel really bad and you probably wouldn't like it, so why make someone else feel bad? Set aside your prejudices and talk to the kid and see what his interests are, you may be surprised at how much you two might have in common. And next time you think of some malicious action to do to him, put yourself in his shoes and think how it must feel to be constantly picked on for being born a certain way.