Bedrock, harder than a motherfucking Flintstone
In stratigraphy, “bedrock” is the native rock underlying the surface of a planet (The Flintstones' hood was a pun! Did you know that?)
Tyler is claiming to be really “hard” (tough)
Or, Tyler might mean by “bedrock” that he actually “rocks” his bed (by having very rough sex) as much as a Flinstone would. He’s probably also referring to his dick when he says “harder than a flintstone”, comparing the hardness of his dick to a rock.
To help improve the meaning of these lyrics, visit "Yonkers" by Tyler The Creator (Ft. Anwar Carrots) Lyrics and leave a comment on the lyrics box