sarcastic_mode.c

bool process_record_user(uint16_t keycode, keyrecord_t *record) {

  static bool modded = false;
  uint8_t base_code = keycode & 0x0000FFFF;
  if(record->event.pressed){
    if(base_code >= KC_A && keycode <= KC_Z){
      modded = !modded;
      if(!modded){
        set_oneshot_mods(MOD_LSFT );
      }
    }
  }
  
  // Rest of your code here ...
  
}