We actually implemented Facebook Connect for April Fool's back in 2010. It was a real app and posted your 4chan post(s) to your Facebook wall.

EDIT: Here's a screenshot -- http://i.imgur.com/p0peJp6.png The best part was the reviews. They were all either 1 or 5 stars. People were shocked it actually worked.

That is so beautifully subtle... just casually sitting there like nothing out of the ordinary.

Hilarious.