the voice with which a kid speaks when conversing with an adult; this voice is marked by faked politeness and is often several octaves higher than the normal voice
Matt: Chris, your grown-up voice makes you sound like a pre-pubescent girl.
A belief that adults can do and saywhatever they want without social backlash or being reprimanded by others for their actions.
When you're a kid, most adults will use their Grown-Up Privilege by making you apologize for swearing, making sex jokes, and for choosing to not play with toys.