I once had a 7-10 year old friend who was totally incontinent. I wasn't his friend until after I learned that though

. I had him over to my house a lot, and I would go over to his. He would always try to hide it, but most people knew. He had a beeper that would go off in the middle of class to remind him to change (terribly embarrassing idea, btw), and would grab his black diaper bag and take it into the bathroom. One time at my house, I also found a wet and poopy diaper sitting open in my bedroom trash can right after he had changed into his pajamas.
I wish I had kept the relationship going. Don't know how many friends he had. He certainly has my understanding. I feel like I owe him an apology though for the way a lot of us (myself included at times, very regrettably) treated him over the issue. Kids do dumb things though...
Not to say I was terrible, I just should have been a better friend in this case. If I were to meet him now I would apologize for ever having made fun of him behind his back, and would show him that I wear diapers too now, even though I wear for slightly different reasons and not necessarily 24/7.