One of the sweetest moments in Flintstones history inspired parents for generations to sing the same lullaby to kids and grandkids. It happened during the 1963 episode "Ann-Margrock Presents," when the sensational star Ann-Margret gets a flat tire that sends her searching for help at the Flinstones' humble abode.

Because she calls herself herself "Annie," Fred and Barney fail to recognize the star, despite the fact that they are preparing to enter a talent show where the winning prize is performing with her. So as the guys get ready to rock, Ann-Margrock ends up bonding with Pebbles, and these adorable interactions lead the famous singer to come running to Pebbles' crib when the baby starts crying.

In an attempt to soothe the wailing Pebbles, Ann-Margrock sings a song that today has a special place in Saturday morning cartoon history, called "The Littlest Lamb."

It's essentially a song about counting sheep, but far lovelier sung by the lilting Ann-Margret. The sequence shows cute lambs hopping through clouds and over hurdles while Annie gently taps Pebbles' belly to help her eyes fall heavy.

As audiences watched, equally lulled, the song ends as we watch Pebbles attempt to hop a hurdle as Ann-Margret dubs her "The Littlest Lamb" – who Annie insists is "too little for such a big leap" (arguably the most enjoyable part to sing). At last, the scene fades back to the Flintstones house, and we see Pebbles "tuckered out." Ann-Margret finishes her song, satisfied she's helped the little lamb sleep.

Of course, the rest of the 1963 episode features another performance that rocked Bedrock a little harder. Fred, Barney and Ann-Margrock perform "Ain’t Gonna Be Your Fool No More," another Ann-Margret number made more popular after she sang it on the cartoon show. After that performance, though, you can tell what the true heart of the episode is, because Ann-Margrock finishes the set by saying onstage goodnight to a very special listener fast asleep in her crib.

You know this episode made an impact on fans, because decades later when Hollywood decided to make live-action Flintstones movies, they tapped Ann-Margret to sing the Flintstones theme song for the sequel, The Flintstones in Viva Rock Vegas.

It was the return of Ann-Margrock, but for parents and grandparents who have been singing "The Littlest Lamb" on sleepless nights since the 1960s, it probably felt like Ann-Margrock never really left.