Top 10 Jay Leno Moments

Frequent guest hosts have long been a tradition on The Tonight Show, and both Carson and Leno served stints as fill-in hosts before landing the gig on a full-time basis. But in the 17 years that the workaholic Leno hosted the program, he permitted only one other person to temporarily take the reins of the show.

In a 2003 promotional gimmick, Leno traded jobs for the day with then Today show host Katie Couric. The morning-show stalwart, who attempted her own monologue and showed off her shapely legs during the program, must have enjoyed the reprieve from waking up early — three years later, she left NBC for an anchor slot on CBS Evening News. While both hosts expressed anxiousness about the swap, they worked out better arrangements than Matt Lauer, who instead traded jobs with a New York City taxi driver. Ouch.