Also I see some irony that when there is a terrorist attack that kills innocent people in Paris, the way to show solidarity is to sing this in football matches:

Do you hear, in the countryside, the roar of those ferocious soldiers? They're coming right into your arms to cut the throats of your sons, your women! To arms, citizens, form your battalions, Let's march, let's march! Let an impure blood soak our fields!