Kiss the cap [verb phrase] To put the cap, or mug, to the mouth. Drinking.
This phrase I faintly remember hearing at one point or another…not to an extent that it is still present in this day and age, but enough that it drew my attention when I saw it listed.
It sounds just a little more scandalous too. I entered the room and my spouse sat rigid in our old arm-chair, kissing the cap with the mug I had claimed as my own.
Kacirk, Jeffrey. The Word Museum: The Most Remarkable English Ever Forgotten. New York: Simon & Schuster, 2000. 107. Print.