Why on Simchas Torah do we through our kids into the air when saying, "משה אמת ותורתו אמת"? Is this is a minhag or some nonsense that someone made up?
My local orthodox rabbi told us that on Simchas Torah, Korach jumps and yells "Moshe emes v'Toraso emes" in admission that he was wrong to rebel against Moshe Rabbeinu. In celebration of Korach's defeat, our rabbi jumps during the dancing in imitation of Korach on the words "Moshe emes v'Toraso emes".
My conjecture is that throwing children is a natural extension of the older custom of jumping. It provides an opportunity to tell the midrash about Korach jumping and provides a fun way to get younger kids involved with the Simchas Torah celebration.
I have seen in a Yeshiva on Simchas Torah that the bochurim sing the words משה אמת ותורתו אמת and while singing jump up repeatedly, similar to throwing the children in the air.
Is the source of this jumping perhaps two gemoros. The gemoro in Bovo Basro 74a
He said unto me: 'Come, I will show you the men of Korah that were swallowed up. I saw two cracks that emitted smoke. I took a piece of clipped wool, dipped it in water, attached it to the point of a spear and let it in there. And when I took it out it was singed. [Thereupon] he said unto me: 'Listen attentively [to] what you [are about to] hear.' And I heard them say: 'Moses and his Torah are truth and we are liars.' He said unto me: 'Every thirty days Gehenna causes them to turn back here as [one turns] flesh in a pot, and they say thus: "Moses and his law are truth and we are liars".'
and the Gemoro in Megillah 14a,
The sons of Korah, as it says, And the sons of Korah did not die. A Tanna taught in the name of our Teacher: A special place was assigned to them in Gehinnom and they stood on it.
So we see that the sons of Korach had a special place in Gehinnom from where they said “ Moses and his Torah are truth”.
Perhaps they were jumping up there to get out of the place and we or our children imitate them?