In a clip uploaded by mum Tara Willmott, the kids argue about whether it's 'raining' or 'drizzling' without even bothering to look out the window.
One of the girls tries to tell the boy that it's raining, but he insists that he knows better because his mum told him it's only drizzling.
At one point he offers a somewhat peculiar line of argument - 'no, you're pretty. And you're not real, I'm real' - before going back to 'it's drizzling'.
The boy becomes increasingly frustrated as the video goes on, when both girls start to gang up on him. One then lightly prods him in the chest.
Shocked by things suddenly getting physical, the boy whimpers: "Oww....you poked my heart."
Story continues after video...
The video has been viewed more than two million times.
One viewer said: "This is so cute! I LOVE this!"
Another said: "The young gentleman put forward an excellent argument, I am firmly behind him and agree it was clearly dwigawing and it was very unfair for the young lady to poke him in the heart!"
And one simply wrote: "These kids are adorable."
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