"...I - I just..."
All eyes are on you. This is SO awkward, but you can't -- no way.
Oh, CRAP! Your bag - ! Kay has it upstairs. So much for a quick escape...
You scramble to your feet, arms unconsciously crossed over your chest. "I j-just need -- to use the bathroom!"
Nearly tripping over yourself, you scramble into the hall where, thankfully, there's a restroom.