What to do if I did not make my high school cheer team because I'm a guy?

In considering what you should do the question arises as to what you want to achieve and what you can prove. When it comes to proving the "real" reason the head coach did not make you a part of the team you may find that what you were told in confidence would never be admitted as having been said when it comes to proving the matter at hand. Absent some type of proof there is little you can do in the legal arena. If on the other hand you just want to get on the team then you can approach the head coach and simple ask what you need to improve upon in order to make the team. If you still feel that you are being kept off the team merely because you are a boy then you may want to discuss the matter with the school administration.

This of course raises issues of reverse discrimination. I do not know if you have ever heard of Title IX, which is legislation surrounding the promulgation and support of women in sports and the isue of discrimination.  Some courts have indeed made the applicability "gender neutral" in their decisions by referring to "athletes" rather than women and clearly the statute refers to sex discrimination and not just to women and not just to regular sports. The school, however, has to be the recipient of federal funds for the law to apply.  So I might talk this over with your parents and seek legal help.  Maybe just a letter or two to scare them will be enough.  Good luck to you.  PS in college male cheerleaders are encouraged and often get scholarship money.  Keep on trying!