Playing on words or speech sounds WordNet 3.0 & Open English WordNet

Word play or wordplay is a literary technique and a form of wit in which words used become the main subject of the work, primarily for the purpose of intended effect or amusement. Wikipedia

Form of wit in which words used become the main subject of the work Wikidata

A technique in which the nature of the words used become part of the subject of the work, such as puns, phonetic mix-ups such as spoonerisms, obscure words and meanings, clever rhetorical excursions, oddly formed sentences, and telling character names. Wiktionary