You know what they say out on the farm: Don’t get between a boy and his horse, ‘specially when the horse is tiny and the boy is Timmy. On last night’s Saturday Night Live, host Timothée Chalamet — an actor as coltish and dear as a tiny horse, himself — starred in a painterly musical pre-taped sketch called “Tiny Horse,” which played to all of his strengths: Dreaminess, acting, aching gazes, forbidden love, youthful angst, having an emotional exchange with a parent, laying back and staring up at the stars in a bed of hay. “Tiny Horse” begins with Timmy learning that his parents are going to have to sell the farm, even the animals. That means Chalamet will have to let his greatest treasure and best friend — an adorable little Claymation horse that lives in a little chest and fits in the palm of his hand — run free. Chalamet loves his tiny, majestic horse, but he has big dreams for it, like graduating from “Animal University.” So he tells it to “go on, git,” with tears in his beautiful eyes, singing a beautiful song. Also, the tiny horse rides a normal horse. We love you, tiny horse.