Nothing's off limits when Jeff Ross goes head-to-head with Blake Griffin in a Roast Battle on Saturday ... including his former relationship with Kendall Jenner.
Here's the deal ... Blake challenged Ross on social media a few days ago. Ross accepted. Now, the joke prepping begins. So does the s**t talking.
"He gets injured easily," Ross said about the NBA star ... "Maybe it'll be an emotional injury this time."
Ross won't have a hard time finding material -- but, our photog gave him a head start.