well here is my 2 cents:
you are a man and man have dicks. general knowledge
one of mans biggest concerns is not to be big enough. you do not have that issue
do not be ashamed of your body ever. wear what you want and act normal. you do not need to flaunt or try to disguise nothing. if your cock had a mouth it would be screaming look at me from those speedos.
what is the quality of the friends that you are going with? just use these rules. good friends? go ahead. co workers? be careful, you do not want to become office fodder.
your mom or aunts or close relatives? try swimming trunks.
on a dating mode? do not use the speedo, wear a thong. this would apply also if you are in st marteen in the french side.