to agree upon a subject as being the most truth or most exciting thing in a subject.
(similar to "fo shizzle" definition, but not exactly) This definition has been around since the early 80's
Example 1: Jason's friend told him, that his friend won the lottery and Jason replies, "Dude, that's the shizzle."
Example 2: Ryan and Mike wonder if Becky has a crush on Mike. Becky approaches Mike and asks him if he wanted to go to a party with her. As soon as she leaves, Ryan and Mike look at each and Mike replies, "Thats the Shizzle." Ryan replies back, "yeah, its definitely the Shizzle".