How quickly we forget.  Amidst all the outrage surrounding Michael Richards's outburst at the Laugh Factory, nobody seems to recall he's done this sort of thing before.  So, to refresh your memory, we bring you...   7 REASONS WE SHOULD HAVE KNOWN MICHAEL RICHARDS IS A RACIST   In season 5, episode 17 of "Seinfeld," Kramer "fell asleep" in a tanning booth, excessively darkening his skin and offending his "black" (really Mulatto) girlfriend's family.   Kramer exploited a black stereotype by dressing as and acting like a pimp in season 7, episode 19 of "Seinfeld,"   In 1994, on a red carpet interview outside of the 46th annual Emmy awards, Richards quipped, "The only black people I find in there better be holding ladles and serving me soup."   In the 1989 Wierd Al Yankovic film "UHF," Richards played a janitor-turned-children's TV show host named Stanley Spadowski.   At one point in the film, Spadowski dons a KKK uniform and invites children to join his "Klan of Krazy Klowns."   Seinfeld co-star Julia Luis-Dreyfus once revealed in an interview that, during season 6 of the series, Richards pitched an idea for an episode to the writing staff in which Jerry has an "Octaroon cutoff," by which he meant that he would not date anybody with more than one-eighth African American heritage.   Richards brutally pistol-whipped comedian Mario Joyner at the wrap party for the "Puerto Rican Day" episode of "Seinfeld" in 1998 (season 9, episode 20). The altercation was covered up and Joyner was never heard from again.   A grainy home video appears to show Richards as a youth spraying a kitten with a garden hose, then beating it with a 2X4 while shouting, "You negroes are not welcome in our schools!"  The authenticity is unconfirmed.   BACK TO HOTBOVINE