You are probably a yeehaw if:
1. You wear a troxel.
2. You jump a horse that is not some kind of warmblood, thoroughbred, or quarter horse.
3. You say things like "how are your hunter-jumpers going?" and when the person responds simply "good" you smile and, not prompted, say "Well my eventing is going awesome."
4. When you say something about horses, people laugh. This is not because you are funny. It is because you don't know shit.
5. You wear a plastic helmet (cover optional to maximize tacky factor) that is color coordinated to match your shirt, hideous britches, loose rubber "boots", and gloves. Your horse's saddlepad, fleece pad, browband, and polos also match your outfit.
6. You dont wear a hairnet and your helmet rests on the top of your forehead. If you do wear a hairnet, it is visible on your forehead and surprisingly not holding your hair back.
7. Your legs swing back and forth at the canter and the word "release" means absolutely nothing to you.
8. You go around to A rated jumper shows wondering why very little paints like yours are showing.
9. You say things like "I've jumped three and a half feet." or my personal favorite, "Oh, my horse jumps like 3'4"." That is not a measurement, dumbass. Figure out why the people with the pretty horses say "oh, three foot. or three foot-six."
10. You are in pony club
It might also be exclaimed by the rider of a bull or bucking bronco at a rodeo or their spectators.
Oft conflated with gee haw: right and left, respectively, TWO commands for controlling a beast of burden with respect to the current path. The current expression is the result of the phonologically entertaining velar abandonment of gee /dʒiː/ for slothen vowel yee