This is very rare vintage Hewlett Packard (HP) Computer Ceramic Thermochromic Coffee Mug celebrating "6 Million LaserJets SOLD"; 

When filled with a hot liquid, "THANKS" appears in place of the zeros in 6,000,000 and then fades to black as it cools back to room temperature.

Great (Christmas) gift for the coffee/tea-loving geek-at-heart, especially if the geek is also "vintage" him/herself.

Condition is "pre-owned" (though not likely ever actually used for coffee/tea) and in excellent, like-new condition; see all photos for condition (and thermochromic effects).