This mug comes from iconic underwear manufacturer Joe Boxer, whose underwear is currently sold exclusively at Sears and Kmart. The Smiley Face logo with the tongue out, as seen above, is part of the Joe Boxer Logo and trademark.
On the reverse is a dark rectangle with the words JOE BOXER TIME! in white. (The words Joe Boxer are in the company's logo font.
When hot liquid is added, the rectangle clears to add the phrase "TIME TO CHANGE YOUR UNDERWEAR!" answering the unspoken question, "What is Joe Boxer Time?'" The mug is in great shape, and color change is quick. It's hard to imagine an underwear company giving out these mugs as employee incentives and little is known as to the actual history of the mug. One site I went to suggested that the mug might have been part of a retail 'gift' combo, underwear and coffee cup - perfect for gift giving.
DESIGN: 1+ Sided
THERMOCHROMIC: 1 Color
TYPE: Retail