I've seen them on a dead run with one foot in the horse's rump and one wrist through a loop in the horse's mane shooting arrows and guns from under the horse's neck.
8 seconds sound clip from the Jeremiah Johnson (1972) movie soundboard.
You can hear this line at 00:18:42.230 in the Blu-ray version of the movie.
Quote context
[...]
- Whatever you learned down in the flat will serve you no good up here.
- Utes and Flatheads are generally peaceful critters.
- Crows, they are fearful. Mighty warriors too.
- But they are an adulterous people. Adulterous.
- Here you are, pilgrim. Sharp enough to scale a fish with.
- Woman?
- I never could find no tracks in a woman's heart.
[...]