Luke 20: 17-18, records some profound and contrasting words by Jesus in which He proclaims that the stone (referring to Himself, the ROCK) which the builders (people) have rejected is become the cornerstone (foundation of God) and whosoever falls upon the stone (Jesus) shall be broken; but on whomsoever the stone (Jesus) shall fall, the stone will grind him to powder (will be crushed).

While the exposition to this text may seem at first as a little difficult to understand, the hidden treasure in these words of Jesus is quite simple. It is as plain as Jesus expressed it.

Whoever falls on (commits their life to) Jesus shall be broken (of their self, the bondage of sin and the seduction of the world). They ironically will be the ones who will be saved.
On the contrary, on whomsoever Jesus (the ROCK) shall fall (as a means of God’s righteous judgment), they will be totally ground to powder (face the full wrath of God’s judgment for not having fallen on (believed in) Jesus).

What does it mean to Fall on Jesus?
It means it is to acknowledge the Lordship of the Sovereign God, and believe that Jesus is the son of God, the savior of the world and confess, so that we are broken from our self, the bondage of sin and the seduction of this world, and totally TRUST in Him. But then again, I think it still falls short of the eloquence and simplicity in which our beloved and wonderful son, Reuben put it – You be the judge of that.

What does it mean to fall on Jesus?
To fall on Jesus means “there is nothing to be worried about, because he will catch you” – Reuben Abishai Paul (Age 3)

Luke 20:17-28 (KJV)
17
And he beheld them, and said, What is this then that is written, The stone which the builders rejected, the same is become the head of the corner?
18
Whosoever shall fall upon that stone shall be broken; but on whomsoever it shall fall, it will grind him to powder.