The words Loose and Lose are mixed up in writing; for some reason, many people write loose when they really mean lose. But there's no reason to lose your mind worrying about this, just lose the extra o! 
Loose
Loose is an adjective, the opposite of tight or contained.
- My shoes are loose
- I have a loose tooth
- There's a dog running loose in the street
Lose
Lose is a verb that means to suffer the loss of, to miss.
- I win! You lose!
- Don't lose your keys
- I never lose bets
The Bottom Line
Simple carelessness leads people to write loose when they mean lose. Just remember that lose has one o, and loose has two. Start with loose, lose an o, and what do you get` Lose!