Cindy Lou Who is the kind-hearted little girl from Dr. Seuss's How the Grinch Stole Christmas, first published in 1957 and later adapted into several beloved screen versions. Because she is normally gentle and sweet, hearing her scream at full volume is jarring in the funniest way, which is exactly why the clip took off as a reaction sound. Short scream clips like this one circulate widely on soundboards and in meme edits, where creators use them to sell panic, shock or playful overreaction. The contrast between the innocent character and the piercing scream keeps it funny years later.