From wikipedia

Doggerel, or doggrel, is poetry that is irregular in rhythm and in rhyme, often deliberately for burlesque or comic effect. Alternatively, it can mean verse which has a monotonous rhythm, easy rhyme, and cheap or trivial meaning. The word is derived from the Middle English dogerel, probably a derivative of dog. In English it has been used as an adjective since the 14th century and a noun since at least 1630.

The Tiger

The tiger
He destroyed his cage
Yes
YES
The tiger is out
— Nael (age 6)
*They're Singing a Song in Their Rocket*