Ass-less What????

I generally quite enjoy the Facebook page "Moms Who Drink and Swear". Probably because I'm a mom who drinks and swears. I do, however, have to take exception to something the head "Mom" said today. She referred to "ass-less chaps". While I think the idea of ass-less chaps is as funny as the next gal, I actually thought for a second. It happens from time to time. Aren't chaps, by definition "ass-less"? Wouldn't PANTLESS chaps be the effect we're going for here? I'm pretty sure I'm right. There you go. An actual deep thought. Discuss. Chaps for all my friends.