Buffy the Vampire Slayer

Willow, in her attempt to get over Oz, casts a spell that ends up causing all sorts of chaos for the gang. Giles goes blind, Xander becomes a demon magnet, and Buffy and Spike fall in love and get engaged.

Later, Riley runs into a starry-eyed Buffy, who tells him that she is engaged to a much older man (although not as old as her last boyfriend).

Eventually, everyone realizes that the cause of all the bizarre occurrences leads back to Willow. Going to her dorm room, however, they find that she's been taken away by a demon.

The demon, D'Hoffryn, having noticed Willow's spell casting and its negative effects, offers to make her a demon like Anya was. Willow sticks with humanity and reverses the spell, causing Buffy and Spike to find themselves kissing.

The next day, Buffy must tell a baffled Riley that she made the whole thing up as a joke.