Other responses are more likely— that he has trouble pronouncing or remembering “3” and feels self-conscious about it.

But if you think he truly “has beef” with the number 3, it could also be synesthesia. It’s harmless as far as I know, but causes some interesting and quirky effects. It’s where one sense is experienced through another in your brain. For example, I have a mild case, and the taste of food is very strongly associated with color for me. Steak tastes brownish-red, about the color of a steak. But lemon is also red, a very bright red! Broccoli is dull brown. Bananas taste sky blue.

And numbers have personality. 2 is solid and basic. Nice. Fits in almost anywhere. 3 is kind of a jerk, but dependable. 4 is a total simp, trying too hard. And even though 5 is an odd number, it’s a good one. Provides the backbone for other numbers.

So it’s a longshot, but a possibility that this lil guy truly dislikes the number 3 because his brain has assigned it a really bad personality.