Is this normal for a boy?

im 14. i want to wear a speedo at the beach and the pool. im sorda muscular(180-190 pounds 6 ft.). so should i. how do i ask my mom to get me one. and another thing. will it effect my penis growth (does tight underwear-boxer briefs) do most boys @ 14 year speedos. what about underwear what type do most wear (boxers, boxer briefs, briefs.) thanks