A little odd but, have you ever, erm sneezed your cup out?
I've got a bit of a spring cold and I've been sneezing all day and just now I was laying here in bed, re-reading A Feast For Crows when I had a sneezing fit and literally sneezed my cup out. It's still partially in, but I'm pretty sure the "seal" has been broken. My cup would likely fall out when I stand up to go to the bathroom to adjust, if I wasn't wearing pants. Has anyone ever sneezed or coughed or anything and caused their cup to come out? Never had this happen before, and it's quite strange.