In case you were wondering just what I did, here are the super simple instructions!
Super Simple Coffee Cozy
4.5 mm crochet hook
small amounts of worsted yarn
2 "nickle sized" buttons (I found that shank buttons threatened to come undone, so I suggest the 2 or 4 hole kind)
ch - chain
dc - double crochet
dc across ch, starting at the 4th ch off hook. ch2 turn work
repeat for 4 rows more, ending row 5 without the ch2 (total of 5 rows) end off and sew in ends.
Look at your work and turn it so that rows 2 and 4 look raised. At one end, hand sew a button on each row 2 and 4. Fold ends together around a mug with or without handles and button snugly, using the dc stitches on the no button end as button holes.