She might be a diabetic and either checking her blood-glucose level or injecting insulin @:-).
Still broadly on-topic but in the past few months I've had a couple of incidences where I've got up to use the lav and seen the "vacant" sign on the door. But on opening the door, there has been a lady sitting on the seat
. Both times they have made me feel it was my fault
FFS, lock the door if you don't want to be disturbed
I was standing in line forever yesterday when the lady ahead of me yanked the door of the "occupied" lav to discover that we'd been waiting behind a ghost.
