Jay Leno And Jimmy Fallon Roast Each Other On 'Tonight Show'

Jay Leno welcomed his soon-to-be "Tonight Show" successor Jimmy Fallon as a guest on the show Monday night.

Leno opened the show by teasing in his monologue: "Jimmy Fallon is here tonight - he's not here to talk, he's helping me pack."

The current host continued, "Jimmy starts the new 'Tonight Show' on the 17th, and it'd be a shame if there was some sort of an accident [where] he was not able to … fulfill his duties as host," Leno added, tugging on his tie knot.

Once Fallon took a seat next to Leno, he was shown his first-ever "Tonight Show" appearance.

Fallon then did a segment in which he wrote funny thank you notes to Leno:

• "Thank you, Jay Leno, for passing the torch to me - hopefully it doesn't get intercepted by a Seahawk."
• "Thank you, Jay, for teaching me how to be a late night host, but was it really necessary for me to wax on/wax off your entire car collection?"
• "Thank you, Jay for giving me such great advice for 'The Tonight Show,' like, 'You don't need a monologue' and 'Have you ever thought about getting bangs?'"

Watch the funny segment below:

Leno's final "Tonight Show" airs Thursday. Fallon takes over on Feb. 17.