0 used when talking about people who believe in conspiracy theories (= the belief that events or situations are the result of secret plans by powerful people), especially to refer to something that protects them from these secret plans:
Remove that tinfoil hat. Seriously, you guys are just paranoid.
Allow me to adjust my tinfoil hat and mention that we're going to have bigger storms now.
She wasn't the usual tinfoil hat conspiracy theorist, though.