There are quite a few different types of headphones, and they all have their fair share of both pros and cons. Circumaural (full-size) headphones typically have better sound quality, but the in-ear kind are much more convenient to wear on the go.
No matter your preference, though, one common problem in pretty much all types of headphones is that if you wear them long enough, they can get uncomfortable. If you're partial to the over-ear variety, redditor Sabre_Cutlass has a solution for you—backer rod.
A backer rod is the foam used before caulking to fill extra space and create an airtight seal. It also just so happens to make a decent padding for uncomfortable headphones, with the added bonus of being pretty cheap (you can get 20ft for less than 5 bucks).
And once it's in place, you'd never know it wasn't part of the headphones.
Quick, simple, and cheap (especially if you already have some lying around). Know of any other great headphone hacks? Let us know in the comments below.