You fill the chamber with used, wet coffee grounds. Wait for it to mostly dry. (may be several days depending on your RH.)
Dump out, rinse with hot water, towel dry, and light up. Right away if you like. No coffee taste. All you taste is the hot water!
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)