Today is Limerick Day. The date honors Edward Lear, the English poet who popularized the short, humorous, and often nonsensical form of verse and who was born on this date in 1812. That's the poetic term for a three syllable metrical foot where the first two syllables are unstressed, or short, and the third is stressed, or long.
Etymologists have two theories.
The other credits a group of 18th century Limerick-based poets. Limericks are famed for their ribaldry and bawdiness.