I find that my hands are usually colder than my feet... I can wear boots on my feet, but I have to have my hands out to do things. And when I have a fun pair of socks I often want to show them off in a more visible way. This really does take no more than three minutes.
Any kind of socks will do, unless they are so small they won't fit on your hands... but of course you can test this before starting.
Step 1: Stitch Up the Heel
Turn your socks inside out. Pinch out the heel area, crosswise, so that the rest of the sock forms a straight tube. Serge or sew across it. No more heel!
Step 2: Cut Off the Toe
Snip! Serge around the new hole at the toe end of the sock, or zigzag if you have a regular machine. Make sure to stretch as you go so the tube is not too tight to fit over your hands.
You can also just leave it raw; the edges may unravel some or they may not, depending on how the sock is knitted and how worn it is.
Step 3: Done!
Turn the tubes right-side out and slide them on! I like to put the old toe ends on first so the ankle part is closer to my hands and shows more.