Anti-pattern where an object's state is encoded across several boolean flags (on_boarded, trial_expired, can_use, subscription_cancelled, subscription_expired, etc.). N binary flags produce 2^N combinations, most invalid or never considered, causing 'combinatorial complexity explosion'. Hidden forms of flags include dates, periods, presence/absence of associations, and status fields. The fix is to make the implicit state explicit via a state machine — system behavior then depends on a single known state rather than ad-hoc flag combinations. Gems like flag_shih_tzu merely standardize the anti-pattern and should not be used for managing state.