Cute. I always enjoy reading limericks. This one follows the form rather well. My one possible criticism of it is that the third and fourth lines rhyme "bought" with "snot" which is a somewhat off rhyme. Come to think of it, I'm not so sure about the fourth line's simile, "yellow as snot". Most of the snot that I've seen is a sort of green color.

Anyway, the fifth line is good, which is generally the most important thing in a limerick.