Always carry a spare pair of breeches!
Why, you ask? Um, in case of funky mounting incidents where the saddle shifts a bit too much on your horse who tends to be a bit cold-backed (and therefore a little goosey at mounting from time to time), and you abort the mount just before getting to the point where you swing your leg over, and during the kick-free-from-the-left-stirrup-and-find-ground-behind-you-with-right-foot sequence, the inner seam on your full-seats gives out. Like six-inches worth, starting at the crotch and going down the thigh.
It was not a pretty sight. Because although if I stood perfectly still and in the right position the tear only looked innocent--or, at least, as innocent as a tear in that location could look. . .
the innocent position
. . . mostly it gaped open, showing the world my winter white pasty looking thigh.
The Quarter Horse saying "Nobody wants to see that!"
I went ahead and rode anyway (riding time is precious!); although I confess it was a kind of drafty ride, and I didn't spend as long riding as I had originally planned because I was worried that someone else might come to the farm and get an eyeful of parts of my flesh that should be covered by breeches.
So, lesson learned. From now on, I will keep a spare pair of breeches in with my horse gear at the barn.