Can someone explain to me what the 9+10=21 joke is about I don't get it!!!!!

Vine

People always say that joke lol

it's a vine

It's not actually a joke. There's a video of two children and one of them thinks 9 + 10 is 21. Apparently it's funny.

it's from a vine

It's a stupid vine where a kid thinks that 9 + 10 = 21.

@Schrödinger k thanks

@🦄immaunicorn🦄 thanks

@Schrödinger umma your a stupid vine

@Sam no need to be rude

@ARMY_ONE thanks

@Waluigi thanks

@Miranda thanks

idk I don't get it either

I don't know myself

@Hey Don't be so pissy. Some people don't waste their time on stupid crap like vines.