Well I am very sorry that your boy had this happen to him Mey. However, I happen to have the same sort of thing happen to my girl last saturday. I was trying to bond my three bunnies together... only the two females don't get along right now and they used to be bonded... and one of my girls backward mounted the other, and got bit right on her *area*. Bonding was put on hold immediately... and all bunnies put back to their room. I watched my girl for the rest of the day... our vets are not open on the weekend, and what can they do really either?? Frodo (the one who got bit) was acting normally as well... eating and drinking just fine. She was even willing to lay stretched out. Anyhow I watched her very closely for a few days... not allowing her out to run around and aggravate the area... and she is doing just fine... the *area* is not red anymore... just pink.... and is no longer swollen. We just put pressure on the area (immediately when it happened) and stopped the bleeding, and then just observed her. My worst fear was that the blood plasma had somehow clogged her urethra... and she wouldn't be able to urinate.
Bunnies are exceedingly resiliant... so try not to worry too much. Your baby is probably fine... but a bit sore and swollen. Hopefully he hasn't had his penis biten off. Just keep an eye on him... and keep him quiet... until you can get him in to the vet. Good luck with everything... I just wanted to let you know that you are not the only one... and that everything will hopefully be all right.