I have a 'phrase arsenal' that I use, one set of phrases for each age group! (4-7) Hey! That's cool! Show me again! Teach me to do that! and others, but that will keep a kid occupied as long as I need it to. With teens, you mostly just have to listen to them talk and say "yeah" and complain every once in a while, or with my friends, I can pretty easily start up a convo in which I can actually feel comfortable, on the scientific american magazine or something of the like. For adults, ask them questions about their job, smile and call them sir or mr._____ and ma'am or miss, depending on age. Tell them how cool their kid is, too, even if you hate the kid. I have trouble with infliction and body language because I stop being able to one hundred percent listen to the words and understand them if most of my focus goes to the 'non verbals'. But, when my scripts run out, I am lost...
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16 years old, I have synesthesia and Aspergers (probably) "I'm not a psychopath, I'm a high functioning sociopath. Do your research."- Sherlock (BBC)