Oh, boy! It's been 25 years since we first met quantum physicist Dr. Sam Beckett (Scott Bakula) and his womanizing sidekick, Al Calavicci (Dean Stockwell), on the NBC series "Quantum Leap." The sci-fi drama debuted on March 26, 1989, and for the next five years viewers followed Bakula's geekworthy time-jumping lead character as he leapt in and out of various decades — and sometimes into history-making events.

Check out the show's opening:

In honor of the cult favorite's 25th anniversary, we pose this question: What if Sam Beckett had never traveled in time? The answer: Well, we probably wouldn't have these things...

1. The Trump Tower and the catch phrase "You're fired!"

Beckett definitely had an eye for the future. In 1958 he pointed out a primo piece of New York property to a 12-year-old boy in the episode "It's a Wonderful Leap." Turns out the kid was named Trump, and he went on to become a real estate mogul who later dabbled in reality TV with "The Apprentice." So yes, we have Beckett to thank for the tower... and Omarosa.

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2. "Peggy Sue"

Buddy Holly didn't write the lyrics to his hit song "Peggy Sue" — at least not according to the "Quantum Leap" version of history. In the episode "How the Tess Was Won," Beckett hopped into the year 1956 and gave the teen songwriter the lyrics to his breakthrough hit song, which went to the top of the Billboard charts the following year.

Watch the full episode of "How the Tess Was Won":

Buddy Holly performing "Peggy Sue":

3. The moonwalk

Who can forget Motown's iconic 25th Anniversary TV special in 1983, when Michael Jackson debuted his Moonwalk moves? Turns out, the King of Pop learned the moves from Beckett in the episode "Camikazi Kid." Of course, the good doc's time-travel machine may have been a smidge off kilter for this event. In the episode, set on June 6, 1961, a young Michael Jackson is a dancing elementary schooler. But the pop icon was actually born on Aug. 29, 1958, so that would have made him only 2 years old. Oh, well, maybe Beckett gave the dance tips to an MJ impersonator.

See the entire "Camikazi Kid" episode:

Check out Jackson's real-life "Billie Jean" moonwalk:

4. The King of Rock 'n' Roll

The 1993 episode "Memphis Melody" had Beckett channeling his inner Elvis, before Elvis was even Elvis. The year was 1954. The place: Memphis, where Beckett leapt into the body and mastered the hip swivel of the future King just two days before he was discovered.

5. "The Twist"

Beckett was clearly a dancing king. In the episode "Good Moring Peoria," he traveled to Sept. 9, 1959, transformed into radio DJ Chick Howell and promptly taught Chubby Checker how to do "The Twist." The real Checker made a cameo in the episode, where he asked if he could use the move.

See Chubby Checker doing "The Twist":

6. A Dealey Plaza debate

The events of Nov. 22, 1963, in Dallas, Texas, were tragic, and no TV show can change that. But President John F. Kennedy's very real assassination had a slight twist in the "Quantum Leap" two-parter "Lee Harvey Oswald." After Sam Beckett leapt in and out of assassin Lee Harvey Oswald's body, he became Secret Service Agent Clint Hill, who, in this fictional account, saved the life of Jackie Kennedy during the motorcade massacre.

The controversial episode went with the theory that there was only one shooter in the assassination, but in an interview with Syfy, Bakula said he didn't necessarily agree with that: "I'm not saying that one man couldn't have made that shot," the actor said. "I don't understand the trajectory of that one bullet. I don't understand now that they've been able to recreate that. I don't know how one bullet does that... I think there's a great desire in our culture to believe there was some sort of conspiracy and that one simple man couldn't get away with that."

[Related: Check Out Photos From 'Quantum Leap']

7. The Heimlich maneuver

In the episode "Thou Shalt Not," a 1974 bar mitzvah had Sam — now a rabbi — saving a choking man by using a unique technique. The man turned out to be Dr. Henry Heimlich, and his method for abdominal thrusts would be published in the Journal of the American Medical Association later that year.

Watch "Thou Shalt Not":

8. Marilyn as a misfit

He didn't have the foresight to save Marilyn Monroe from her untimely death, but in the episode "Goodbye, Norma Jean," Beckett did leap into the year 1960 and become a bodyguard to ensure that the movie icon completed her final film, "The Misfits." The film was poised to showcase the blond bombshell as a serious actress, but sadly, she was dead a year-and-a-half later.

Check out a clip from "The Misfits":