Need: White coffee mug, sharpie
Draw on your mug and stick it int he oven. 350 degrees for 30 minuets. Simple?
Let them completely cool down before you wash it.
*You must hand wash them. This is the only downside. I put everything in the dishwasher and the ink came right off. HAND WASH ONLY!
You can try Pebeo Markers, which I've heard hold up to a dishwasher, but I have not personally tried it myself.
Here are some other examples I've found that are cute: