From Longman Dictionary of Contemporary Englishdangerous ground/territorydangerous ground/territoryRISKa situation or subject that could make someone very angry or upset Teachers can be on dangerous ground if they discuss religion. → dangerous
Examples from the Corpus
dangerous ground/territory• Discussion had ventured into dangerous territory.• It is a scouting reconnaissance into un-known and potentially dangerous territory.• Mr. Lawson moves on to what I regard as even more dangerous territory.• Probably because for Marc it was dangerous ground.• Second, that any official who ignores them is on dangerous ground.• I release my safety belt to hold you, dangerous ground, ground where my feet have wings of flame.• They must also enter the dangerous ground of anticipating the techniques which might be available in the future.• Here we are on dangerous ground, though.• You're on dangerous ground when you talk politics with Ed. 