I googled it and it's a thing in Christianity. Basically making up words to an unknown language. Try praying in Latin without knowing it and you're praying in tongues.
I was raised in a church where tongues would often happen, and I got in trouble for questioning what or why they were obviously saying just gibberish.
Like the whole collapsing on the floor and speaking in tongues while shaking. Do people really just...do that? Like, is it something most people could be pushed to do? Is it actually just a big lie? A performance? Does the pastor ask them to act in such a way before the sermon?