This classic riddle about a tomato turning red is often shared as a joke but I never really understood the logic behind it. What is the explanation or punchline of the “why did the tomato turn red” riddle?

Haha I remember this from grade school! The punchline is pure wordplay. The humor comes from giving human emotions and reactions to a vegetable (well fruit technically). The tomato "turning red" is what tomatoes naturally do when they ripen but in the joke it's because it's blushing from embarrassment or surprise.

Think of it like this: if you were about to be put in a salad and someone was pouring oil and vinegar on you you might blush too! It's an example of an "anti-joke" in a way—the setup makes you think there might be some scientific or clever answer but it's just a silly pun. These jokes are less about "getting" a logical explanation and more about enjoying the absurd mental image. My dad still tells this one followed by "Why did the banana go to the doctor? Because it wasn't peeling well!" Same kind of thing.

I always took it as a joke about social anxiety! The tomato is like a shy person who gets embarrassed easily. Seeing the "salad dressing" (the act of getting dressed) makes it self-conscious so it blushes (turns red). It's a playful way to anthropomorphize food.

The joke works because it subverts expectations. When you hear "Why did the tomato turn red?" you might think of a biological reason like sun exposure or ripening. The punchline is completely unrelated to science relying instead on a human emotional response tied to a pun. It's a gateway joke that leads to other vegetable puns like "What do you call a fake noodle? An impasta!" Don't overthink it—just enjoy the groan-worthy humor.

Oh that's a classic children's joke/riddle! The full version usually goes: "Why did the tomato turn red?" ... "Because it saw the salad dressing!"

The "logic" is a pun based on a double meaning of the word "dressing." In one sense "salad dressing" is the sauce or vinaigrette you put on a salad (which often contains tomatoes). In the other sense "dressing" can mean putting on clothes or getting ready. So the joke personifies the tomato: it "saw" the salad getting prepared (the dressing being put on) and it "turned red" either from embarrassment (like blushing) or because it realized it was about to be eaten and was "dressing" for the occasion. It's a play on words rather than actual logic.

There are variations too like "Why did the tomato turn red? Because it saw the blender!" (implying fear). Or the longer joke: "Why did the tomato turn red? Because it saw the salad dressing. And why did the lettuce blush? Because it saw the salad dressing too!" It's meant to be silly and lighthearted. These kinds of jokes are often a child's introduction to puns and wordplay. You can find more classic food puns like this on joke websites dedicated to clean simple humor.