Season Two

When She Was Bad
Xander performs a little hop-shuffle-bop while mocking Willow with his ice cream cone. Work those arms, Xander. I bet he can do a great robot dance.

Also in When She Was Bad is the famous/infamous Xander-Buffy dance. Buffy cashes in the dance raincheck she gave Xander in the episode Angel, and in a big way. Notice Xander's clear discomfort. This is not the way he wanted to dance with Buffy; he wanted to really dance when she wanted to dance with him specifically. Instead, he can tell something's wrong. Buffy just uses him to make a lurking Angel jealous.

School Hard
As Willow and Buffy study French, Xander shakes his hips on the dance floor. A few minutes later, he persuades them both to come dance with him. He didn't want to be "all alone out there," for he needs support and attention...and dance partners.

Inca Mummy Girl
His first "serious" dance - His slow dance with Ampata. Unfortunately, she ends up trying to suck the life out of Willow and then Xander.

Reptile Boy
The frat guy told Xander to "Dance, pretty boy!" and he did -- in drag! This was merely minutes after he fell through the open window, clutz-like, into the frat party. Xander's note to himself: Do not join a fraternity in college. They will make you dance in ways unlike even you.

Lie to Me
This episode offered viewers a dancing-into-the-lounge Xander, as he suggested a 'crazed dance party at the Bronze', a 'very calm dance party at the Bronze', and finally 'moping at the Bronze'. His idea of a cure-all is obviously some sort of dance party.

Ted
His famous Buffy-directed "You're having parental issues! You're having parental issues!" dance was followed by a "Xander!" scold by Willow. He promptly replied, "What? Freud would have said the exact same thing...except he might not have done that little dance." Ah, the philosophy of dance according to Professor Harris.

Surprise
While preparing for Buffy's surprise party, Xander asks Giles, "Are you ready to get down, you funky party weasel?"

Passion
Xander can be seen rocking out in the beginning of the hour, not knowing that Angel is checking out his every (dance) move...