Click the green flag, type a keyword that is 1, 2, 3, or 4 letters long, press enter, and wait. If it's too long, or it's not all lowercase letters, the generator will run forever.
See the Infinite Monkey Theorem: https://en.wikipedia.org/wiki/Infinite_monkey_theorem If a monkey starts banging away at a typewriter, what is the probability of him writing an entire, cohesive, fully readable novel?
