This also works for shears and clippers that might have debris build-up. Making cleanup easier, it'll also help prevent staining, corrosion, and other wear.
Unsticking LEGO blocks is another well-known use for WD-40. Anyone who's played or built with LEGOs knows how this happens and it's impossible to get them apart.
According to the company, you use the straw attachment to shoot some WD-40 into the crack between the two blocks to work in some of the liquid and they should easily pry apart.
This method involves spraying the entire outside of a baseball glove so that it's thoroughly covered, then wrap it in rubber bands and leave it overnight.
Only leave it for one night, and the new glove stiffness should wear down a bit. After that, play with it like the pros do so that it forms better on your hands.
Hoodies, jackets, luggage, pants, dresses, and essentially any other item that has a stuck zipper can benefit from a little spritz of WD-40 to untangle it.