I made this coffee cozy for my sister's boyfriend. Although the prior one I made for her is cute, I thought he might want something a little more manly to use. I simply used 1 inch Velcro instead of a button to hold the flaps together. It's still adjustable without looking too cute. I used left over scraps from the crib bumper and baby burper projects.
Update: It appears that cozy isn't wide enough to simply use velcro in place of a button. At least not a fit for Coffee Bean and Tea Leaf cups.