Learning that fat meat is greasy, which means learning something the hard way, is a common idiom used almost exclusively in the African-American community, and refers to a juicy cut of the pig called fatmeat. Linguist Geneva Smitherman has a great...
The admonition “you don’t believe fatmeat is greasy” is found almost exclusively among African-Americans. (Sometimes written as “fat meat is greasy” or “fat meets greasy” or “fat meets the greasy.”) The idea is apparently that if you don’t believe...

