Dorm mates

You walk Dow a long hall of dorms with room numbers. He stops and turns to your direction “What’s your dorm number?”
“30b” you respond. He kind of chuckled. You follow him a little further until you stopped at your dorm.
“Welcome home” he walks in and plops down on the bed across from yours. You look and see a picture of him on the wall standing next to what you assumed was his mother. You realized that he was your dorm mate.