I have two boys 14 and 18. One is now in college. Both very involved in sports, have much experience in locker rooms and public showers.
Their penises have been a non-issue in their lives. Although the boys shower after sports (track,hockey, soccer), the guys normally cover up, and those who don't don't prance around. Guys just don't comment on each other's junk. It's uncool.
Please parents, do not live in fear of the mythical locker room teasing. A kid who is going to be teased will be teased for many things, but the penis status is so far down the list. Your child may be teased for having red hair, for being fat, big ears....any number of reasons except for the penis which is 99% of the time tucked safely inside your son's pants.
And the fact that ds's penises are different than dh's? Again, a non-issue. They haven't seen his penis since they were about 5 or 6, and he hasn't seen theirs. When they were young, they DID notice how big and hairy dh's was but that was it.
Don't give in to fears that most likely will never come to be.