Green’s Dictionary of Slang

(US black/campus) to tease.

1960		oral testimony in Lighter HDAS II.
1974		H.L. Foster Playin’ the Dozens 183: The term ribbin' or ribbing is used in Buffalo to describe the verbal game of taunting, denigrating, or making fun of someone [...] In the primarily white northern suburbs of Buffalo, New York, the game [. . .] is referred to as mocking out.
1991		Eble Campus Sl. Mar.
1994		Parade 4 Sept. 19: You don’t have the right to mock out that religion [HDAS].
2001		Michigan Daily 5 Jan. letter 🌐 I distinctly remember when MSU fans mocked Robert Traylor by bringing buckets of KFC chicken to their home games, or times when they made signs saying ‘Remedial Robinson’ to mock out Rumeal Robinson’s learning disability.