Just found that on some old Lifehacker post: a smart way to prevent headphone or earphone cables from becoming entangled.
- With your right hand make devil horns (third and fourth fingers tucked, second and fifth extended)
- Use your thumb to hold the earbuds against your palm
- Wrap the cable around your 2nd and 5th fingers using a figure-8. This is really the key part, the cris-crossing prevents it from knotting
- When you have 6 to 8 inches of cable left, wrap the remaining cable around the center of the figure-8 a few times
- Tuck remaining cable to taste. Somtimes I tuck it through one of the figure-8 loops, sometimes through the center wrapping, sometimes not at all.
Tightness of the wrapping determines how well it holds together, but if you use a loose wrap, you can just pull on the earbuds and the whole thing comes undone without a single knot.