Mermaid Man is the elderly, forgetful superhero from Nickelodeon's SpongeBob SquarePants, voiced for years by Ernest Borgnine, and his confused outbursts became some of the show's most quoted moments. This one-second 'Bonko' line took on a second life on meme soundboards, where uploaders clipped it as a funnier, more characterful stand-in for a plain bonk or slap sound. Because the voice is so recognisable, it works as an instant nostalgia hit for SpongeBob fans while still landing for viewers who only know it as a goofy cartoon bonk.