If you browse through Pinterest, I'm sure you already saw this pin. The other day I went to the dollar store and bought a white coffee mug, and tried it myself.
It took me a while to draw the perfect mustache :o), first used a pencil, then I trace it with the sharpie marker, next put it inside the oven at 350 F for 30 minutes. Let it cool
After you use your mug gently hand wash and let it dry.
Aren't these just too cute? :)