The little balls of deodorant that form under the armpit from applying too much or, for those who choose not to shave, from having too much pit hair.
Chris: Hey man what is this under my pit! I have lint.
Steve: Oh no dude that's underarm armor, you are now forever protected from the evil perspiration monster.
Steve: Oh no dude that's underarm armor, you are now forever protected from the evil perspiration monster.
by Mrs. shaky bacon December 8, 2009