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Following is an example as best I can remember it, taken from the early 1970's, in a casual game with neighbors in the Quad Cities (Illinois/Iowa). All four were good players. This play is elementary to most advanced bridge players, so if that's you, you might be wasting your time reading on.
(Most of South's reasoning and analysis was gotten from the post-mortem after the hand.)
South (the neighbor in question) opened with a strong-two bid, the standard strong two-club bid not being used at that time (at least not in that group). North (my mother) replied 3 Hearts, which promised 9 to 10 high card points and a five-card suit. South wasted no time jumping to Blackwood, where she found that North had one Ace and one King. At that point, she could count 12 tricks: 7 trump, and three aces and two kings in the other suits. She stated later that she figured that the 13th trick might be made if North had a helpful Queen, if the hearts broke 3-3 or possibly even 4-2, or if North had a jack or two, and a missing finesse card was onside (in West's hand). She bid 7 spades.
West made the standard opening lead of the King of Diamonds, which of course also marked her for the Queen of that suit. South won in hand, and then studied. With West marked for the Queen of Diamonds, she couldn't promite the Jack-Ten in Dummy for a trick. With no obvious 13th trick in sight, and only two entries to Dummy, the possibilities appeared to be for Hearts to split 3-3, the Queen of Hearts to drop in two rounds, or to play a finesse through West. She drew trumps, played the Ace of Hearts from hand, and then played a heart to dummy. When West showed out, she knew that she could no longer make a heart good. The next opportunity was for a misplay by the defenders. She won with the King of hearts and played the 6 of Hearts from Dummy, hoping East would follow low and give Declarer a free trick. Unfortunately, East was wise to this and covered the 6 with her 10. South ruffed in hand and studied again. About a minute later, she smiled, nodded her head, and continued with trumps, with both defenders making the best discards that they could. This led to the following position with four cards left.
For a double squeeze of the variety shown here to work, Declarer needs four elements: two individual menace cards (one against each opponent), a common menace card against both opponents, and communication between the hands in order to execute the play. Dummy's red Jacks were the menace cards against each defender's Queen of the respective suit, the common menace card was the third club in South's hand, and communication would be with the Ace and King of Clubs. As a side note, the contract can be defeated by the opening lead of a club, as that would destroy the communication between the North and South hands. However, very few defenders sitting West would lead a club at trick one.
At this point, South played her last trump. West was squeezed. If she discarded the Queen of Diamonds, South would have the last three tricks, in order, with the King of Clubs, Ace of Clubs, and the Jack of Diamonds. West, who knew this, made a face at South and discarded a Club. Now the Jack of Diamonds could no longer be turned into a winner; it was of no further use to Declarer and was discarded from Dummy. East now faced the same squeeze. If she threw away her Queen of Hearts, Declarer would take the last three tricks with the King of Clubs, Ace of Clubs and Jack of Hearts. East rather half-heartedly also discarded a Club.
With the defenders down to two Clubs each, South played a Club to the Ace, a Club back to the King, and her last Club, catching the two useless red Queens held by the defenders and making the grand slam.