One-night stands with pop stars, childhood stardom, and illegal activity over the border: Mario Lopez's new memoir is one juicy tale. The Saved by the Bell alum, 40, gets candid in his book Just Between Us, and stopped by The Ellen DeGeneres Show on Thursday, Oct. 2, to tease out some of the highlights. 

"When a man turns 40, it's an important time to pause and reflect on how he got there, and to make a mature plan for the future, and what better way than to write it down?" Lopez told Ellen DeGeneres of his decision to open up in the memoir. "People have asked me a bunch of stuff over the years… it's stuff I could really get into in the book as opposed to having the opportunity on TV. When I decided I was going to do something like this, I just said, 'Alright, I'm going to be unfiltered and just put everything out there." 

One such tidbit that Lopez unveiled in Just Between Us was about the star's father, Mario Lopez, Sr., and the work that he did to make ends meet for the family. 

"I was born in Chula Vista, [Calif.], which is the border town to Tijuana, and I'm a child of immigrants," the Mexican-American actor explained. "My dad did what he had to do to take care of us. Often times when we'd take little trips across the border — and this was obviously pre-9/11 — we'd come back right away. He'd pull over and he'd open the trunk and sometimes people would come out."

"I was like, 'Alright,'" Lopez continued. "I didn't think much of it as a kid. Then I got older, it kinda dawned on me."

After that anecdote, DeGeneres then prompted her guest to speak to a romantic encounter that he also wrote about in the book. 

"You also admit that you had a one-night stand with a major pop star," DeGeneres questioned.

"Well, yeah," Lopez confessed, confirming that the rendezvous took place in Las Vegas. "I'm trying not to give too much away without giving too much away… it was maybe six or seven years ago… eight years ago?" 

The Extra host when on to add that he and his former flame are still "friendly," but refused to answer if he had interviewed the unnamed singer in the years since they slept together. 

DeGeneres went on to throw out a few names as possibilities for the woman, guessing Britney Spears, Christina Aguilera, and Celine Dion. Lopez shot back, joking, "Barbra Streisand!" 

Watch the video above and tell Us: Who do you think the pop star is?