When a man and woman are having sex 'doggie-style', with the man wearting a condom, and the man says,
"Oh look, a disappearing panda."
And when the woman turns to look at the man, he quickly pulls out, removes the condom and snaps her in the eye with it.
As in the previous example, which did not state the sex being engaged in was 'doggie-style',
"I can't believe how dumb she is. I actually pulled a Disappearing Panda on her last night."