13. Lifeguard

Swimming Trunks, $240
First Aid Kit, $8
Flotation Device, $14
Whistle, $5 

Four words: mouth-to-mouth resuscitation. Grab some red trunks and squeeze a dab of zinc oxide on your nose — this simple costume is good because you start out half naked. It just make things easier that way. Ed. Note: Fat dudes and dudes with backne might want to leave this one alone. Let adult swim commence!