Probably. Or just plain stupidity.
I was riding a gelding leading four mares to their pastures. Bareback. Amigo, my mount, was kind and sweet enough the mares would accept his presence. One of the mares stopped to scratch an itch. I, being stupid, held on. Amigo kept going, and I slid off. Flat on my ass. The mares giggled. Amigo stopped, took one look at me, and the thought bubble over his head said "You're an idiot."
Turned the mares out, then Amigo taught me that I could, in fact, ride a canter bareback.
Not much sex there, other than I should have - would have, given what I know now - gone out at night and pleasured a mare or two.