The SNL alum was cracking grammar jokes on Twitter .. when someone asked, "is this how you spell lasonia?"
Steve's response ... "It depends. Are you in an African-American neighborhood or at an Italian restaurant."
Seconds later the 68-year old actor deleted the tweet and apologized. But the floodgates opened, the original tweet went viral and Martin atoned again: "I did apologize. But again, a second later I realized what an offensive thing I'd done ... In retrospect, bad joke.