Shiny red dress
Fallin’ on the floor with her.
While he hides the details, the singer does explain that when he gets to the top of the stairs and takes his pants off, the girl is wearing that shiny (silk? latex? rubber? leather/ette?) red skirt, and they tumble to the floor in passion.
I would have suggested that her shiny and red dress suggests some sluttiness on the girl's part. Her distress in the next stanza, however, clouds that issue.
1) Is she playing the part of the tart, but like him is not wholly prepared for the situation, especially when the singer climaxes?
2) Is she actually a slut, but is mad because he's not using protection or climaxes too soon?
3) Is it just a fecking red dress?