Some of these glasses were called “peek-a-boos” and featured a clothed pin-up image on the front, usually a decal, although some were hand-painted. On the back side of the decal, the idealized woman would be depicted in sexy lingerie or plain naked. Her state of undress would increase as you drank.
These collector glasses provide a peep show from a more innocent time.
Link Warning: nudity.
Ouch! Sucks to loose such an heirloom.