why Why WHY!?!??!!!!!

WHY IS IT THAT EVERY TIME I GO INTO A PUBLIC RESTROOM WITH ONLY ONE TOILET SOMEBODY WILL START RATTLING THE DOORNOB THE SECOND I SIT DOWN, AND WILL DO IT OVER AND OVER NO MATTER WHAT I DO, APPARANTLY DEAF AND NOT BELIEVING THAT ANYONE COULD HAVE EVER GOTTEN THERE BEFORE THEM?!!?!!?!!!!!