When two males are having intercourse with one female at the same time. The female is giving slobbery felatio to one male while the other one is bumping uglies (vaginal or anal) with her from behind. Before the males have their sweet eruption of ejaculate, they lock arms above the female - resembling a Texas Longhorn Bovine. This term might be more relevant and used in the Southwest region.
"Last night me and my homeboy were banging this chick: he was getting some head while I was pounding it out from behind. We reared back and reached across the bitch and slapped a high five. It totally looked like a Longhorn. Then me and my homey came all over her face. We so pulled a Longhorn High Five on that chick."