I found my son in bed with his best friend (male) naked during a sleepover. I woke up at the middle of the night and went to go see if they were asleep and found them. What should I assume? Should I punish him and contact his friends family? I feel like a disappointment letting this happen in MY house. What should I do.
Don't panic. It may or may not be an issue. The most important thing is to establish a strong relationship with your son. Being his mother will help because the subject is less confronting when it is the parent of the opposite sex talking.
Given he is a teen, it can be a confusing time and may just be a phase on the way to working out where on the range of behavior he is. It is better to underreact and build up your concern than overreact and drive a wedge between you.
He may feel annoyed that you were "checking" on him. Did you have any suspicions that led you to check on them or was it complete shock that happened because you were innocently just being mom?
Maybe open honestly with how you found out and then explain how others may see it, then take it gently from there.
Good luck, it's a tough one but may end up being a good outcome.