Since childhood I have heard that when you are buried in your grave, the zameen (ground) squishes you 3 times to the extent that your mothers milk comes out of your mouth. Is this true?

If yes, then dont you think its illogical because we have no other choice but to step on the ground. We cannot fly.

I have not heard this in the way you are presenting it. We do have narrations about the squeezing or tightening of the grave due to ones sins.