You may want to double-check that 19th-century picture of your great-great-grandfather. A portrait being auctioned on eBay conceals a naughty secret.
Unusual Early "Secret" Nude Print, mid-19th century. It appears to be an ordinary portrait print of a young gentleman in a birdseye maple frame, but a notch on the upper back allows the portrait to be pulled up revealing a hand-colored and rather explicit lithograph. 16.25" x 13.25" overall. [Link]The unpixelated photo is not suitable for work, home, or anywhere else.
Update: I missed this note on the portrait's condition, which proves that the naughty secret was not so secret (emphasis mine).
Appears to be all original, with expected toning to both prints; portrait has worn losses from many years of pulling it up to reveal what is underneath.
[via Boing Boing]