D.O.N.T. (Disturb Opponents' NT) is one of the most effective defenses against a strong 1NT opening. Here's how it works:

(1NT) — 2:    Shows clubs and a higher suit.
2:    Shows diamonds and a higher suit.
2:    Shows both majors.
2:    Shows a weak hand with spades.
X:    Shows any one-suited hand.

The advantage of D.O.N.T. is that it lets you find any fit with partner on the 2-level. This makes it safer to overcall with a weak hand, since you won't end up in a doubled 3-level contract. The disadvantage of D.O.N.T. is that you cannot make a penalty double of a 1NT opening (since a double shows a one-suited hand). This drawback makes D.O.N.T. impractical for use against weak 1NT openings, where the penalty double is essential.


        Finding a Fit.    After the initial overcall, responder has the following options:

(1NT) — 2 — (Pass) — Pass:    Shows club support.
3:    Shows great club support and a weak hand.
2:   Denies club support, and asks overcaller to bid his second suit. 
2NT:   Shows a strong hand with interest in game. 

After the 2 bid, overcaller should pass if his second suit is diamonds, and bid his second suit otherwise.


        Showing a One-Suited Hand.    With a one-suited hand, you should begin by making a double. This is not a penalty double, and shows no more strength than a typical overcall of 1NT. Your partner should then bid 2, at which point you will either pass (with clubs) or bid your suit:

(1NT) — X — 2Pass:    Shows a club suit.
2:    Shows a diamond suit.
2:    Shows a heart suit.
2:    Shows a spade suit.

        NOTE:    With a spade suit, you can simply overcall 2 to start with. Hence, some partnerships assign a special meaning to the auction:

(1NT) — X — 2 — 2