Ever since my oldest kid was born, I've been warned about the teenage years. When I talked to people about my kids, some of them seemed to relish warning me about the upcoming teen years. If one of the kids got a little sassy, people would remark, 'Just wait 'til they're teenagers!' I'd get the same response if a kid were throwing a tantrum or doing pretty much anything negative.
I have always thought the phrase "Hire a teenager while they still know everything" was a very clever sentence. It works on the premise that teens think they always know best and, therefore, think they "know everything." It may be funny, yet it belies a real truth, which is that teens often act as if they know more than they do. Think about the last time you tried to instruct an adolescent about something.