Roommate walked in on me masterbating

Pretty much exactly what the title says. He left for class and I thought I was in the clear, but turns out he forgot something and walked in on me with it all out :( It’s a small room, classic college double, so locking the door wasn’t an option. I’m not necessarily ashamed of masterbating, but I’m still a little embarrassed and especially nervous about how he might take this. Any advice?