John Matta draws cartoons on napkins daily. The results are simple and hilarious. In an interview about his work, Matta tells the story of how he got started:
Two years ago I was eating at a Subway and watching a mother demand that the guy behind the counter give her free meat samples. She wanted to let her little boy taste them before ordering. If the child didn’t like the meat, he’d spit it out on the counter. If he liked the meat, he’d also spit it out on the counter, accompanied by an approving grunt.
It was the most wonderful thing I’d ever witnessed. I felt I had to document the event so I drew it on a napkin. Then I started drawing more stuff on napkins. I kept showing them to my wife and finally she said, "You should really show these to other people besides me." So I set up a blog and began posting them.
You can find his full archive of cartoons at the link. Be warned: you'll be there for at least an hour laughing.