Harry has extreme claustrophobia, so he tries to avoid tight spaces as much as possible and he had managed it. But of course, Draco and Harry have to have gotten locked in a closet together. It's extremely tight, especially with two 15 year old boys inside it.

Draco: "For Merlin's sake! I don't even know who I'm in here with!"

Draco says angrily as he pulls a string, turning on a light