childish. If you act immature or bratty, you're being childish. A childish dinner guest might pout because you didn't make dessert. While the adjective childish is sometimes used to simply mean "like a child," it's more common to use childlike in this way.
When someone is acting very childish and irresponsible. Aswell as being a bit stupid, you reply with childish gambino as to get the message across without them being offended.
Sarah “Hey, I have commitment issues but gonna blame them on you. Then I’ll spread hate about you.”