Your OPP takes a moderately unexpected action in third seat after two PASSes.
You decide quickly what your action will be if the auction PASSes back to you (In fact, you had anticipated that this suit might be bid on your left when you PASSed initially and had selected a response before PASSing). However your partner is caught a bit off guard and emits a bit of UI before PASSing. Now your RHO PASSes and it's your turn to act.
You believe that your partner's UI suggests the action that you had previously decided to take and that taking a different action is likely a logical alternative to the action you had previously chosen.
Should you
Benefits include:
Plus... it's free!