Lose one's shirt

Can anyone tell me what the phrase 'to lose one's shirt' means?
Thanks,
App

When you were in a card game and "took a bath" and you "bet the ranch"
and lost you would then proceed to "lose one's
shirt" on your next hand.

Let me clarify Bruce's answer a bit. To lose one's shirt is to lose everything you have, literally or figuratively, to someone else. It's a bit of an exaggeration to lose your shirt, since someone would normally only take your valuables. Maybe if it's a really nice shirt...