I want white teeth when my braces come off. is it bad that i drink coffee?

Two issues: Coffee only produces external stains on the teeth which can be minimized with proper brushing and flossing and can be removed with a professional cleaning. The more you drink the greater the chance of staining.The inherent shade of the teeth is a separate issue. There are many whitening methods to permanently whiten the teeth. Discuss all this with your own dentist after the braces are removed.

Yes: Along with not brushing, smoking, etc.