Here's the image in question. Winry's the one that's face down, and the characters from left to right after that are Bradley, Alphonse, Kimbley, Lust, Archer, Hawkeye, and Havoc.
Based off of "The Yes Dance" by Robert Hoffman.
Here's the video (sorta NWS for swearing and eventual nudity):
Yeah, just don't ask. XD