Pop Culture Ref Source: "Mmmnyes?"

I have this habit of answering calls from friends/knocking on my bedroom door with a hum that flows into a drawn-out "yes?" so that it sounds kinda like "mmmnyeeeesss?" I'm sure it's something I picked up from a movie or a TV show, but I cannot for the life of me figure out exactly where. Does this ring a bell for anyone? The only result I've been able to find when I try to look it up is Homer Simpson, but that's not it. I'm leaning more towards it being from a retro cartoon, but that's all I've got.