Twitterers last night collectively gasped at the sight of a big-bottomed birthday-suited girl alleged to be sex-tape thespian Kim Kardashian, but were quickly disillusioned: The photo proved to be a year-old twitpic snapped by porn star Amia Miley.

The adult actress expressed confusion over the mistaken identity, tweeting "apparently a naked photo of me eating is going viral...as Kim Kardashian." As proof, Miley pointed to "the back dimple piercings," which she assured "kim k doesn't have."

TMZ initially claimed the photo was originally tweeted by none-other-than Kardashian's beau-du-jour Kanye West, but quickly revised their report to say that West had nothing to do with the pic.

"We're told it's all part of #WanksterWednesday," TMZ wrote. "A prank day where people try to get bogus rumors started."

Quite the challenge.

UPDATE: It seems the pranksters picking of Miley for this gag was no coincidence: The Italian/Hawaiian babe once starred as Kortney KardASSian in a Hustler porn parody.

[photos via @amiamiley, @KimKardashian]