The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a well-established method for the prevention of sudden cardiac arrest and an alternative to the transvenous implantable cardioverter-defibrillator (TV-ICD). It is preferred mainly for young patients with long life expectancy, high risk of transvenous lead complications or history of previous endocarditis, or device infections. For both S-ICD and TV-ICD, inappropriate therapies are possible. For S-ICD, the most common cause of inappropriate shocks is T wave oversensing (TWOS), while in TV-ICD – supraventricular tachycardia. We present the case of a 38-year-old patient who reported a shock during physical exercise - crunches.