Have you seen the "Mental Age" videos that are all over TikTok right now? There's a website called "A Real Me" that has a free test you can take to see what your mental age is.
It doesn't have to do with I.Q. It's all about how mature or immature you are compared to other people your age.
The test defines "mental age" as your psychological abilities compared to the, quote, "number of years it takes for an average [person] to reach the same level."
It's not clear how scientific it all is. But people have been posting their results on TikTok. Or you can also just take the test and not share it.
It's 30 questions, mostly true or false. Things like, "Could you kill a cockroach with a book?" and "I like to be friends with [people] older than me," true or false?
At the end, it tells you your mental age. Like, you might be 36, but your mental age is 44. So you're a little more mature than other people. Or if you're 28, you're hip and young at heart.