It is the idea that certain beliefs are outside the Overton Window [1] of acceptable political discourse, but you want to signal your endorsement of that belief

It is the idea that certain beliefs are outside the Overton Window [1] of acceptable political discourse, but you want to signal your endorsement of that belief to your supporters without saying it outright, to preserve plausible deniability. [1] https://en.wikipedia.org/wiki/Overton_window https://en.wikipedia.org/wiki/Overton_window