fo shizzle my nizzle translates into "I will definitely acquiesce indubitably in the said activity such as drinking cool aid, grape soda, orange soda, KFC, watermelon, waffles, and various other food items".
Boo: Yo, would you like to participate in the consumption of Kentucky Fried Chicken, while consuming a 40 oz alcoholic beverage in the back of my vehicle that has the bass so far up that whenever I commute near a seismographic station, there seems to be a 10.7 on the Richter scale in Ethiopia.
La Fawnda: Fo shizzle my nizzle.
Boo: Well, that sounds swell to me. Let us hop in and endear in the lovemaking in the opposite sex.