A Marty Bergen/Eric Rodwell convention! Partner opens one of a suit, and your RHO jumps to 3♦, 3♥, or 3♠. DOUBLE is a THRee no trUMP (THRUMP) double:
Partner opens, RHO overcalls. What does a DOUBLED mean? There is definite disagreement in serious bridge circles as to the requirements for a negative double. CHECK ALL THIS with your partner early on!
You and partner are bidding a major suit. The opponents are bidding a suit just below your suit. How can partner tell the difference between (1) you competing for a part score, versus (2) making a real game try?
LHO Opens, partner overcalls, and RHO bids a new suit. You have 5 of the unbid suit and tolerance for partner's suit. What do you bid???
A support Double or Redouble occurs as opener's rebid. You open one of a suit, partner bids a new suit, and the opponents make a bid.