It’s called a backwards attack and happens when you are crossed up and the game determines that you are on the wrong side that you want to be on. It can happen with any type of attack, normals that are standing or crouching, special moves, and even jumping attacks. Usually you see it happen after a jumping cross up. The move you want comes out as an opposite animation because the game registers you as not completely crossing over your opponent and switching sides. Sometimes this can be good, like doing repeated splashes as Papasi stated above. However sometimes a move coming out backwards can cost you the match.
YuuVega doing [media=youtube]d9aNUyfjhRk"]backwards instant overhead magic in the corner. Komoda doing a backwards jumping short kick after a cross up. Jason Nelson gets himself an [attack after a cross up that leaves him open. I don’t usually keep track of backwards moves so this is all I could think of off of the top of my head. As your can see the first two examples help the person, the last one was not intentional at all.
There’s actually a perfect example of Yaya doing cross up tiger knee tricks to get Aniken’s dragon punch to come out the wrong way but I don’t know which video it is. Anyone know that one?
[media=youtube]m9enJ6ZFpvE"]Backwards moves](http://www.youtube.com/watch?v=rFjnNU99Z6Q&#t=1m47s"[/media) are all over combo videos as well and you can see them in [URL=“http://www.youtube.com/watch?v=pN5JjotDMAg”[/media] as well. NKI Volume X has quite a bit, Blanka doing hop tricks to force Ryu’s dragon punch to come out on the wrong side, Zangief blocking Fei’s flame kick behind the back, Ken jumping under Dictator and getting a backwards vertical attack.