DONT

In the card game contract bridge, DONT is a conventional overcall used to interfere with an opponent's one notrump (1NT) opening bid. DONT, an acronym for Disturb Opponents' Notrump, was designed by Marty Bergen, and is therefore also referred to as "Bergen over Notrump". Although the method is often criticized for being too nebulous, it remains fairly popular. The convention was first published in the September/October 1989 issue of Bridge Today.

In DONT, the two-level overcalls of trump show a two suiter of the suit bid and an unspecified higher-ranking suit. The feature distinguishing DONT from other similar conventions such as Cappelletti is the use of the double to show length in one suit, rather than hand strength or for penalty. DONT is played mainly for interference rather than to establish a contract, so it may occasionally be used for low-strength hands.

DONT can be used with low hand strength, but intervenor must have good suits when vulnerable. DONT features the following calls:

Preferences vary as to the use of the 2♠ bid. Some treat it as weaker than the sequence of a double followed by 2♠; others play it as showing a solid (runable) spade suit; other treatments are possible and partnership discussion and agreement is necessary.

DONT is normally applied as a defense to strong notrump opening bids, but some people have created various modifications to DONT to apply them to weaker notrump openings. The difference is that the bidder shows opening-bid values and the partner of the doubler may pass to convert the single-suited hand into a penalty double.

Against the mini-notrump opening bid which shows 10-12/13 HCP (also known as the Kamikaze 1NT):

There are variations in the agreed responses, and partners should establish a clear agreement.

One common system of responses is:

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