Witherspoon, 36, honored her pal Aniston, 42, at ELLE's 18th Annual Women in Hollywood Tribute at the Four Seasons Hotel in Beverly Hills on Monday.
Taking the podium to introduce Aniston, the recently remarried "How Do You Know" star looked back on how they became fast friends following her nerve-wracking guest appearance on "Friends" way back in 1999, when she played the frosty, high-maintenance younger sister to Aniston's Rachel Green.
"I just had a baby [daughter Ava, now 12] and I could not stop watching Friends," the Oscar winner confessed. "I was super duper excited y'all!"
The major hitch, once she arrived on set? "In all my enthusiasm, I completely forgot something crucial...I had never been on television [or] in front of a live audience ever in my entire life. And I panicked! I totally froze!"
"I couldn't remember my lines and the writers were yelling ... I just stood there absolutely completely frozen."
Cue huge sitcom star Aniston, who pulled the newbie aside and said "'Hey, are you okay? You're kind of freaking me out!'"
Aniston offered Witherspoon some crucial advice. "[She said], 'You're going to make a mistake and you're going to flip your line and whatever -- and the audience is going to love it,'" Witherspoon recalled. "'Don't try to be perfect, just try to be yourself.'"
"That's the story that sort of captured Jen the best for me," Witherspoon explained on the podium. "On one hand, she is this gorgeous breathtaking beauty that men lose their thought process and their speech patterns [over]," she gushed of the star, now dating Justin Theroux. "I've actually seen this, it's incredible when they see her. And, on the other hand, she is a woman who lets you in."
"There's not that many people actually that have this incredible combination of sex appeal and complete lovabililty," she said of the Horrible Bosses actress. "You just want to get your nails done with her, and you want to make out with her at the same time . . . at least I do!" she cracked.
"First we get our nails done, then we make out!" she joked. "It's totally awesome. That's because she's MY friend, not yours!"
Aniston was appropriately thankful once she accepted her award. "Good Lord, Reese Witherspoon! Wow. I adore you and I thank you for those beautiful words."