My favorite bid in bridge: the takeout doubler makes a subsequent double which is penalty. Generally this only happens against me and one or both of the opponents has a misguided idea of what the doubles mean. And often times I get doubled by such opponents when we have an actual fit but I go down 1 and get a bad score.

An example of this is 1D-X-2D-P; P-X-P-P; P. OR 2H-X-3H-P; P-X-P-P; P.

If you make a takeout double, and then later double the same suit again, it is not a penalty double. I've seen this work both ways. One where the doubler's partner bids and the doubler thinks his 2nd double, with something like a 15 count and 4 good trumps, is penalty. And I've seen it where the doubler's partner leaves the double in with a nothing hand, thinking it was a penalty double, but in fact the doubler has an appropriate 17 count.