A teenager’s new vocabulary can be an attempt to build a place among peers.

Language is one of the first things people use to belong. Words arriving suddenly in a young person’s speech are usually less about the words than about membership: this is how my friends talk, and talking this way is how I am one of them. Mocking it tends to be heard as mocking the belonging, which is why the reaction can be so out of proportion to the correction. The vocabulary will change again within a year; the need underneath it will not.

If this is happening near you, ask about the words rather than about the grammar. Curiosity keeps the door open longer than correction does.