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 . DONT is played mainly for interference rather than to establish a contract, so it may occasionally be used for low-strength hands. The convention. DONT can be used with low hand strength, but intervenor must have good suits when . 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 . Against the mini-notrump opening bid which shows 10-12/13 HCP (also known as the Kamikaze 1NT): Responses. There are variations in the agreed responses, and partners should establish a clear agreement . One common system of responses is: Over strong club opening bids. When the opponents play Precision Club or other strong club system, 1 usually describes a 17-19 point hand. Accordingly, DONT can also be employed over these types of systems. Variation. A variation of the system, claimed to provide additional disturbance of the notrump auction, calls for the partner of the intervenor to bid his cheapest doubleton when the intervenor has shown a single-suited hand. This relies on the Law of total tricks to find adequate protection at the three level. The variation does have a few risks , for example if the partner of the intervenor has two short suits the fit in the agreed suit may be deficient.