Most stories say Loki thought he could outrun the stallion. He could not. He got fucked by a horse. All to keep his buddies from owing some guy money. Oh, yeah, and he got pregnant. With an eight-legged horse.
All the saints and grape juice in the world don't hold a candle to the murderhorse.
It Gets Weirder
The horse he gave birth to grew up to be Odin's horse. Imagine if you got raped by an animal, got pregnant and had a son. An eight-legged monster-horse son. And your friend saw him and said something like, "Hey could I have that? He could sleep at the foot of the bed!" That's the kind of weird relationship Loki and Odin had.
Artist depictions get a little insane at this point.