One day Pebbles Flintstone was in bed with Fred and Wilma. They were both naked. Pebbles sees Fred's penis and says, "Daddy, what's that?" and Fred says "Th-that's...um...thats daddy's rock." A little while later Pebbles looks down and sees Wilma's vagina. "What's that, mommy?" she asks. "Oh..that..that's mommy's rock grinder." All of a sudden Pebbles sits up and says, "I get it! Daddy puts his rock into mommy's rock grinder and out comes pebbles!"