Towser is the scruffy cartoon dog from the British children's books by Tony Ross, who later starred in his own animated television series, where gentle mischief like startling a friend fits the show's playful tone. The 'boo!' followed by Sadie's extended scream became a favourite on soundboards because it packs a full prank into under six seconds. Creators reuse it for fake jumpscares, meme edits and reaction clips, where the over-the-top scream sells a shock that is clearly meant to be funny rather than frightening.