Child Assists Avengers at Birthday Party, Boots Thanos in the Head

Ah, if only this kid was around at the end of Infinity War.

A comical video being shared on Reddit on Friday showed just what happens when a supervillain messes with a child's favorite heroes.

Shot at a kids party, several costumed members of the Avengers — and for some reason, one member of the Justice League — have assembled to take down bad guy Thanos.

And it appears they have been successful too, as Iron Man, Spider-Man and Captain America look on victorious, while the universe-traversing event MC Batman, who despite being the least super-powered of the lot, has somehow managed to pin the purple Titan to the ground.

Perhaps sensing the mismatch, one young sidekick from the audience springs into action to assist the Caped Crusader... by running up and landing a full-force kick to Thanos' head.

Chaos ensues as his little pals take cue, sprinting up behind him and stomping the helpless baddie into the ground.

The other Avengers can only look on in shock at the violence as the tiny vigilantes dole out pint-sized justice, while laughing parents do their best to heave their offspring back from the melee.

Despite his small stature, the youngster managed something Hulk, Star Lord and even Captain Marvel couldn't even do: keep Thanos floored.

As the top commenter pointed out, the boy wisely followed Thanos' own advice when mocking Thor's first failed attempt to kill him:

"He went for the head."