-Isocolon is when at least two portions of a sentence are completely synonymous in either rhythm, structure, length, or a combination of these three. Basically, isocolon can be classified as a form of repetition that does not require words being repeated over and over. This rhetorical device can be frequently found in music, poetry, speeches, and slogans. Depending on how many phrases comprise the sentence, isocolon may be referred to as "bicolon" (two parts), "tricolon" (three parts), "tetracolon" (four parts), etc.
-A "literary" example of isocolon can be found in John F. Kennedy's 1961 inaugural address. Here, the former president implores his "fellow Americans" to "ask not what your country can do for you--ask what you can do for your country (Kennedy).
-A visual example of isocolon (or here "tetracolon") can be seen in this vintage Dr. Pepper linked below. In the commercial, the singer's jingle, "I'm a Pepper, she's a Pepper, he's a Pepper, we're a Pepper" is an example of the rhetorical device's frequent appearance in advertisements.