I worked at Chicago O'Hare airport long before social media and 9/11, and even back there were signs warning that joking about or even mentioning bombs, guns, etc. could result in being questioned by police. Of course it's more pronounced now, but honestly, if you joke about terrorism at an airport (or tell a sexual or racist joke to a co-worker for that matter), do you really think no one is going to react negatively? Or that no one should react negatively?
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