When using the term “corny,” you apply it to something repetitive, immensely sentimental, or downright cringe. It may also be something subjective and be utilized for something that does not click with you.
In the world of rap, the term is used similarly, especially with lyrics, rhymes, verses, and beats. Corny does not equate to bad automatically. The rap might just be too cliche, overused, or cringe to some extent. If it does nothing unique, does not have an edge, or is very much basic, it might be corny. Ludacris, Machine Gun Kelly, Drake, and many more have been labeled as such. You can use this slang this way:
“The rap part of Bieber’s Baby is so corny that I get some shivers whenever I hear it!”
“I think some of Eminem’s work is corny such as “Not Afraid.” I think he does become too emotional and sobbing that he loses his edge.”