floater
DEPOSITS OF VARIOUS SIZE, SHAPE, CONSISTENCY, REFRACTIVE INDEX, AND MOTILITY WITHIN THE EYE'S VITREOUS HUMOUR, WHICH IS NORMALLY TRANSPARENT
Floaters; Eye floater; Muscae volitantes; Muscae volantes; Mouches volantes; Eye floaters; Myodesopsia; Muscae volantites; Vitreous floaters; Flying flies; Weiss ring; Eyes floater; Eyes floaters
1) A partially-finished and unclaimed bottle or can of beer.
Whose floater is this?
2) When you and your friends have an inside joke and an outsider doesn't get the meaning then she is subjected to a floater. The meaning is from something that was over their head.
The reference comes from the idea that something over your head can float by like a balloon.
We had a good laugh over the joke but Susan only got a floater.