You learn to be yourself. Love who you want to love. Be who you want to be. Who cares what other people say? Are you living to make other people happy, or yourself? Go for it! Tell him how you feel! If he doesnt feel the same, at least you gave it a shot and wont live to regret not doing so.
If you're worried your friends will make fun of you....maybe they're not your friends If you're worried about what other people will think AT ALL, then maybe you're not mature enough for a relationship......VERY FEW of the people in your life NOW will be there down the road later in life, so don't worry about what "they" think and do what YOU wanna do.....life's too short to worry about other people's opinions....
Feel the fear and do it anyway. Ask yourself, what's the worst that can happen, if the answer is death then skip it, otherwise remember your life is a journey so take some risks and have fun along the way.
If you're friends make fun of you for liking a guy they aren't real friends. But if you really like the guy then I suggest you tell him. Who knows, he may like you back and if you avoid him and never tell him he'll move on. (Trust me I kept avoiding this guy that liked me and he doesn't like me anymore, I wasn't doing hard-to-get its just that I didn't like him back) so tell him and good luck.