When some boring bastard calls you immature it may piss you off a bit. Some people act like they are thirty when they are eighteen, you are only young once and you might as well enjoy it. Really, why would you want to act like an old fart before your time?
I knew a girl, Jana, who was constantly telling people to stop being immature and grow up. She was twenty-one and told one of her friends, Sasha, that she needed to start thinking about settling down. Sasha had other ideas, she traveled the world, went back to school and made the most of her twenties. Jana, on the other hand, married a total loser and had a kid at 22. Her husband became a heroin addict, she had to divorce him and became a single parent. Not exactly a sparkly fairytale for someone who thought she was more mature than her friends.
Enjoy every stage of your life and if someone gives you a hard time about being immature, smile and know that you are having fun.
The next time someone calls you immature, use one of our clever comebacks.