My 14yo brother isn't horsey in the least, but is capable of handling my easy going on the ground mare, and can even catch her, soak her hoof in water/epsom salt for 10 minutes, and turn her back out no issue. My horse also knows that "down" means for her to lower her head for what ever.
My brother helped me feed tonight, and I asked him to take the grazing muzzle off of a horse. He walks up the mare, undoes the snap on the muzzle and says "down" to her. He waits, then says again "Horse, please put your head down." This horse has no idea what "down" means, and continued to wait for my brother to reach up and take her muzzle off.
After a bit of giggling I told him that the horse in fact had no idea what he was talking about and he pulled the muzzle off over her ears. I was still impressed though that he remembered that my own horse is so user friendly.