In my younger years, I would not stand silently during the sirens on Yom HaShoah and Yom HaZikaron. After all, I reckoned, those are non-Jewish, meaningless customs. Instead, I would recite Tehillim, the traditional Jewish way of memorializing the deceased, which actually helps them in the Upper Worlds. (Of course, if I was in public, I would nevertheless stand in silence out of respect for others.) Such is still the normative attitude in the charedi world.