Young male with one testicle

That's a good question.

Surely there is some sort of support group for this type of man.

I would think that your GP or family doctor would be able to connect you with some group or supporters.

The other side of this is that a man with only one testicle is not all that obvious.  There's no real way to look at someone and "know"... unless you tell.

PS: There may be issues of fertility later, but many a man has had children when they have only one functioning testicle.

Look at http://groups.yahoo.com/group/SoloTesticleGuys/.  I have one testicle and have put pictures in this group.  There are several guy that have posted.