The mysterious case of my trouser button

I was standing in front of the urinal after having just finished my wee. I went to button up my fly and felt the top button pop off (I blame the poor stitching!). I looked down and the button was no where to be seen. Puzzled, I proceeded back to the dancefloor. After a few minutes, I felt something in the bottom of my left shoe and realized it was the button! How the hell did it manage to land in my shoe??!! I surmise that it had either slid down my left trouser leg or was catapulted directly into my shoe.