Mission trip. Could I pack briefs?

I am a junior in high school. I like to wear the fruit of the loom and hanes kind. I am afraid if the other boys in the same grade will make fun of me. I will room up with three guys. I don't know who yet. the church is filled with preps and jocks so? I normally sleep in my underwear also. Would they tell anybody about it? I can't stand boxers.