Yeah, it's completely normal! I get this all the time, and I absolutely hate it
You're right about the breifs part. It'll keep it closer to your body so you won't make a tent in your boxers. You can also wear exercise pants over your breifs so it'll be even harder to see.
In the morning, first thing you should do is don't lay on it
. It makes the erection bigger and last longer because you rub against the bed. Try laying on your side and don't touch it to see if it goes away in 5 minutes. After that, the only way is to sneak out without your friend noticing it. You can run, and if you walk, you can sorta lay your hand with your palm facing out to try to hide it. That's what's what works for me =]