This move is exclusive to Terence and can only be done on an enemy who is bent over. The input is (standing beside the enemy)

and the direction towards the enemy. Terence jumps over him to the other side. Certain moves can make enemies bend over, the most common is the special attack (

) of Bud but they can do it randomly as well. You can try for this two ways (other than just getting it randomly if you play Terence anyway which is totally possible):
1, Play on hard and wait for the enemies to bend over then do it on them. Since they have a lot of health someone will survive long enough - eventually - to suffer it twice.
2, Play on easy, walk into the biggest crowd and do left/right +

a lot. Usually enemies return to standing position after one horse attack but sometimes not and eat another. When I got it. I did one, did the second out of habit and the guy ate it before stood up.