(Courtesy of Bob Crosby)
When the opponents open 1 or 2 forcing it should be like waving a red flag in front of a bull. At favourable vulnerability and at times equal, you should have a weapon of choice to disturb things. Tom Gandolfo and I use SUCTION as a way of being un-invited guests. Suction is basically bidding the suit under the suit you have with a one suiter (simple transfer). However, Suction is an either or bid. If you do not have the one suiter, you indicate the two suits above that suit using the rank order of suits.
Responding using Suction is to assume that partner has the one suiter until you hear differently. Its when you have that suit or one of his possible other suits is the time to have a field day. You super accept into the "other suit" which he may have assuming the one suiter. If he has that suit, all well and good. If he does not, he bails to his single suit which you also have. A win win situation.
Example:
1 | 1* | Pass | ? |
* Spades or Clubs and Diamonds
You have xxxxx x Kxxxx xx, I would leap to 4. Partner has spades or the minors. If he has spades, he corrects which is happiness. If he does not have spades, he has the minors so we are well on our to being an irritating nuisance to the opponents.
The purpose of Suction is to disturb the opponent's auctions. Therefore the ACBL has barred the convention except when the opponents open a strong artificial club opener. You can also play Suction as a tool when the opponents open 1NT but with restrictions. The ACBL demands that you play "simple suction". They only allow the first step (2) which shows diamonds or the majors. All the other steps are just simple transfers.
Over 1 or 1 response the double is always the first step showing the suit above their suit or the suction suit combinations.