I second the recommendation to snap the lid and use an airlock. If it's a hefe then you might want to use a blowoff, or if it's a 5 gal batch in a 5 gal carboy I would advise a blowoff. A loose lid on a fermenting bucket will only tempt you to constantly peek, all the while possibly exposing your wort to nasties. If there's some one else around, they might even do something silly like stick their finger in and give your brew a swirl, just to see how it tastes. Don't laugh, it's been done before.