Yep, I lost mine after two years (which was a record for me), I don't even know when it slipped off, I had it while gallivanting around, pretty sure I had it on the bus home but not 100%, and then I got home and didn't have it.
J had a few near misses (his slipped off at the beach a few times) but in the end it came off when he was gardening of all things and he couldn't find it.
Guess you'll have to take a sickie or a long lunch :)