* Playing with them: A curious dog might pick up a glass and drop it somewhere, or chew on it, leading to it being "hidden" under a couch or behind a curtain.
* Accidental knocks: A playful dog might knock over a table or shelf, causing glasses to fall and get lost.
* Hiding from their owner: A dog might hide somewhere to avoid being scolded or to play a game, and accidentally bring a glass along.
If you're looking for lost glasses, it's best to check common places where dogs like to explore or hide. And, of course, make sure to keep glasses out of reach of your dog!