This phrase was developed by Dan Harrington and he used it to describe the fact that the first player in the game to open a hand, all in or raise has an advantage and all player who wager after him will need to have significant better hand to call his raise than he required to make it.
This will prompt them to fold cards which will otherwise be playable. This will be of importance when the tournament is almost coming to a close of when one has a stack that’s small compared to the blinds. This happens because the player will have less time to wait for a good hand and thus have the benefit of going all in first. This will put pressure to players with valuable stacks and on the other hand he will use the fact that the players who are after him will not be in a position to call with a suitable hand as there can be players after them who will be able to call with a good hand. This will make them fold plenty of hands that they would have otherwise raised.