Prince Go-for-It knelt in a teammate's discarded gum, then, trying to be helpful, removed the bulk of it, leaving a ground-in gum stain instead.
I searched the internet and found several recommended solutions, most with very mixed reviews as to the effectiveness. There was so little gum left, icing it didn't help, because there was not enough left to peel off. I was afraid to try any of the oily hints (WD-40, peanut butter, etc.), and trade the gum mark for a grease spot.
Hot vinegar sounded like it might work, as it was supposed to dissolve the gum off the fabric, but I was upstairs, and felt too lazy to deal with the heating and all involved. When I saw the Windex hint, I thought that sounded like a close alternative... and easy to do while sitting right there on my bed, watching Castle. ;-)
I'm happy to report it was a success! When I finished, and put them in the washer, I could see a tiny hint of the spot's outline remaining.
The prince ran off with the pants as soon as they came out of the dryer the next morning, so I didn't get an "after" picture, but Go-for-It says he couldn't see any evidence of the gum, and was happy to look spiffy for his next game.