Bladder
You're going to be nervous and you'll probably reach for anything that will quench your dry throat, but don't reach so frequently that you can't make it through the wedding ceremony (approximately 30 minutes for most, though some can run longer).

Digestion
Watch out for anything before the ceremony that could send your bowels into overdrive. Nobody likes a gassy groom.

Excerpted from The Groom's Instruction Manual by Shandon Fowler. — 2008 Quirk Books.