Body and beads, I stain my sheets, i dont even know why. My girlfriend, she's at the end, she is starting to cry

The story:

My friend had actually convinced me that the song was about sex, specifically with, um, beads. And there I was, signing along, and when we came to that part, I oh-so-wisely shared my "knowledge" with some people (fortunately people that I knew) around me. And I was so, so wrong...