My boy friend is my roomate now and we wear each other's clothes all the time. He's about my size now so it works out pretty well. Years ago he was kind of big a muscular and I was quite thin; as time past, he got thinner and I've gotten fatter
A few years back, we were staying at a motel. He was working construction at the time and it was summer. We'd taken off our clothes and were in bed. He needed more cigarettes and I needed more beer. So I got up to go to the 7/11 next door. I thought it would be a thrill to put on his clothes instead of mine.
At that time he was a lot bigger and his clothes were kinda funky from working outside all day. Anyway, I put them on and went to the 7/11. It was a thrill and the whole time I had to keep holding his pants up so they wouldn't fall off.