text: Yes, I have.  I was bitten on the leg.  It's pretty bad stuff.  It starts rotting the skin in and around the bite itself.  Swells up really huge, like a boil.  The longer you wait to go to the doctor the worse it si on you.  Considering your friend was bit on his buttocks, he had better get on in to the doctor.  They will lance it and put you on antibiotics.  Seek medical attention!!