When your coworker says "what kinda flashlight you got in your left jacket pocket 'cause I know you have one in each pocket" and you pull out a flashlight from that pocket....
When your wife calls you a 'battery whore'.
When you're wife asks you what you want for Christmas and you tell her you already bought it. And she intrinsically knows it's a flashlight.
When you get together with friends you only see once a year and instead of saying "how have you been?, they say "what is your latest flashlight and how many Lumens does it put out?"...
When your cellphone has a shortcut to the general flashlight discussion forum and the led flashlights forum on the home screen.