Instead of blinking at them or winking at them or just blowing them off. Read this report of the Munich killer, which includes the following:
On the day of the [Munich] attack, according to the newspaper Bild, Sonboly told associates via a computer game message: “Come to the McDonald’s and I will come and get you and shoot you.” At the time they dismissed it as “hot air” as similar threats had been made before. A teenage girl who lived in the same apartment block said he had told classmates: “I will kill you all.” Four of the teenagers, all friends, killed by Sonboly were named last night as Can Leyla, 14, and his friend Selcuk Kilic, 15, both of Turkish origin, and two girls: Sabina Sulaj and Armela Segashi, both 14. A fifth member of the group was critically injured.
We need to start taking these threats seriously.