Declarer leads the A, parter plays low, dummy plays low. Do you discard the Q or the T?
Since you have to discard a non-small card declarer will know you have either a singleton, or QT doubleton, because with any other holding you'd play something else. If you have T singleton, there is nothing declarer can do about it except lead small to dummy's J at trick 2. However, if you can convince declarer you have Q singleton, the right play is to hook the 9 in dummy. Thus, playing the Q at trick 1 is a mandatory false card - discarding the ten will never gain, discarding the Q puts declarer on a genuine guess.
At very high levels, this gets further randomized because declarer will pickup on the Q likely being a MFC, and thus work to otherwise resolve the guess and get it right (e.g. play other suits and using deductive reasoning from that. - so at very high levels the winning strategy is actually to make the MFC most - but NOT ALL - the time, at random.
On the other hand, for the declarer it is just business as usual: you try to navigate the tricks making as few guesses as possible. At some point realize that seeing the Queen doesn't always mean a singleton, so you put that in the "guess" category, but the actual process isn't effected.
Nope, what is it? Nothing shows up in my Google searches other than plain old "false cards", which are fairly obvious. I don't remember bothering to name such a thing.