This is a vintage coffee mug made by Thought Factory.
It is beige and says "#1 DAD" on the front with a scene of a father attempting to assemble a complicated toy for his son and daughter.
This standard size, 10 ounce mug was made in Japan.
It measures 3.75" tall and 5" wide including the handle. The top opening measures 3" in diameter.
This mug comes in good pre-owned condition.