Academic explanation for rhyming fillers with irrelevant meaning in doggerel 在打油诗、顺口溜、儿歌里经常有纯粹是为了押韵或节拍而插入的和文意无关的词汇。在北方话、传统北京/天津评书相声里尤甚。我想知道在语言学专业里这种情况是怎么解释的，有没有术语或相关资料。

例如北京顺口溜：


  嗝屁着凉大海棠，脚不丫子蘸白糖。


里“大海棠”完全是为押韵，无意义；蘸白糖虽然略有意义，但选词十分随机，更多是为了一种插科打诨的效果。

Brief translation:

It's common to hear rhyming filler words without a relevant meaning being used in doggerel/jingles, especially in Northern China dialects and traditional Beijing/Tianjin storytelling and cross talk performances. I am wondering if there are linguistic terminologies, theories or reading materials around this.

(The example is a Beijing doggerel. The point won't hold after translation.)
Regarding "The point won't hold after translation", maybe the words in this poem are relevant:

See you later, alligator!

After while, crocodile!

In an hour, sunflower!

Maybe two, kangaroo!

Gotta go, buffalo!

Adios, hippos!

Chow, chow, brown cow!

See you soon, baboon!

Adieu, cockatoo!

Better swish, jellyfish.

Chop chop, lollipop.

Gotta run, skeleton!

Bye-bye, butterfly!

Better shake, rattle snake.

Our school day now ends.

So, good-bye, good friends!