It's the silly, sing-song taunt he uses when he's about to hit someone (usually with a fake slap or a toy) or when he's playfully mocking someone — often followed by "¡Toma, toma, toma!" (Take that, take that, take that!).
I think you're referring to the (or "Acumalaca" / "Acoomalaka") sound effect, which is famously associated with Don Ramón (Ramón Valdés) from the classic Mexican TV show El Chavo del Ocho . Acumalaka sound effect