These tea cup cozies are awesome. I have one (you can see it here), and I use it every day with my morning coffee. They're cozy (hah, get it?), soft, warm, and serve as built in coasters - and, you won't be holding a piping hot mug of coffee, tea, hot chocolate, or cider with your delicate bare hands! Plus, they look cool. Your friends will be jealous.
I made a few minor adjustments when making mine:
-dc 12 in first ring
-hdc after second dc ring
-sc around in back loop of hdc for a more distinct bottom "corner" edge
I made 9 rows of grit stitches to make the cozies this height. I've made shorter and taller ones, but this height seems like a good middle ground for a range of standard mug sizes.
This item is stretchy, and slips right over top of your favourite mug.
Sloshed your coffee down the inside of your cozy on your way to your comfy livingroom chair? Just throw it in the washing machine and dryer.
I fully recommend this pattern. If you're too lazy to make one of these adorable tea mug cozies for yourself, at least come to the craft show and get a few for your friends... They'll love you more because of them. ;) (And, you can help fuel my crocheting obsession!)