Green’s Dictionary of Slang

(US teen) insincere talk used as a brush-off to an unwanted advance.

1960

Baltimore Sun (MD) Sun. Mag. 4 Dec. 9/3: The C.P.B. that Twitter gave the boy when he bugged (approached, annoyed, interrupted her) was the Certified Pure Bull. [...] you cool the one you love, and the rougher you chill him the better he likes it.