feigned madness
assumption of a mental disorder for purpose of evasion, deceit or the diversion of suspicion, also a strategy—often institutionalised—in order to acquires a privilege to violate taboos on speaking unpleasant, socially unacceptable truths
en-GB/ˈfeɪnd ˈmædnəs/
en-US/ˈfeɪnd ˈmædnəs/