It's not an African-American dialect for all of you who have assumed such a position. It's more a regional dialect and drives me crazy! I am an African-American from New England from a very affluent Maryland family. We abhor the grammatically incorrect phrase. My english studies has always deemed the phrase "on tomorrow" grossly incorrect. But I've observed colleged educated (many many teachers) Baltimore/DC metro area people of all ethnicities and cultures using the phrase. The experience is like nails on the chalkboard to me as well. But truly, it's not a big deal. :)