Here's a hand that came early in a $3,000 buy-in World Series of Poker event, a six-handed no-limit hold'em tournament.
In the hand I was dealt on the button where I had about 38,000 to start. With the blinds 150/300, a tight-aggressive player with only 6,000 to begin min-raised to 600 from under the gun. The next player over in the hijack had about 25,000 and three-bet to 1,600 and it folded to me.
The stack sizes matter here. The three-bettor probably has something decent. He knows that the original raiser could go all in, and so is likely ready to call with his hand.