A double of a game (or slam) contract in the expectation that the opponents could make a Small Slam (or Grand Slam) and in the hope that they will accept the apparently good score for making a doubled game (or slam) with overtricks rather than go on to the higher-scoring slam.
The convention takes it name because the doubler flees like a ‘striped-tailed ape’ in the face of a redouble. The doubler will need to have an escape suit, or a good fit for partner’s suit. The stripe-tailed ape double is a type of psychic bid.
For example:
West is almost certain that North- South can make a slam and so doubles 4♥. If North redoubles, West retreats to 4♠. The penalty in 4♠ doubled will certainly be less than that in 6♠ doubled and probably cheaper than defending 6♥.