A Compact Multitool
While many modern multitools are designed for your wallet or keychain, a pocket offers much easier access (and quite frankly, less valuable real estate). A credit card multitool like the 12-in-1 PocketMonkey fits like a hand in a glove, though traditionalists can opt for an old-school pocket knife. (Our preference is for Opinel.)
If you aren't familiar with solid cologne, prepare for a revelation. With a range of crisp and woodsy scents, these fragrances from Alfred Lane are more subtle than liquid cologne, but have to be applied more regularly (every few hours or so). Thankfully, the waxy base and handy tin are eminently portableand fit perfectly in your fifth pocket.
A Smartphone Battery Pack
You may carry around a charging cord, but there are countless situations where an outlet is out of reach. Luckily, a fifth pocket is perfectly suited to a lightweight smartphone battery: A mophie Power Reserve packs a 60-percent charge, or you can opt for the versatility of a Native Union Jump Cable, which has a charging cord built right in.
While most guys could benefit from a daily activity tracker, not everyone wants to advertise his brand new pursuit on his wrist. The FitBit One is a compact alternative that's as small as a stick of lip balm, and fits perfectly in your fifth pocket to track your every movementwhether your phone is with you or not.
Copywriter, cold brew advocate, purveyor of handcrafted birthday haikus since 2009.