Pass is normally the weakest option in any Chilli auction, but if we are already in a game force then pass over their bid is forcing, with the message that neither a penalty double nor an offensive bid is obvious:

WestNorthEastSouth
1123
pass
A forcing pass, unsure of how to proceed, so effectively a takeout double.

Sometimes a pass will be right when you will get another chance:

WestNorthEastSouth
12NT
?
2NT is minors. With a moderate hand, tolerance for spades and a heart suit you would like to make a takeout double, but double here is train-the-guns showing good values. The best action may be to pass, and then to double for takeout on the next round.

With a trump stack over RHO's bid, pass may be the only option.

WestNorthEastSouth
22
?
Responder with a fistful of spades has to pass and rely on partner to re-open with a double.

NEXT: disturbed two no-trumps