Slang

When did you stop talking like a school kid? Do you remember when you stopped using the slang that was once cool? One of my friends asked me, and I couldn't answer.
Everyone must have noticed that the younger generation uses their own jargon: speech which has a unique meaning with very limited usage among kids of that generation only. Sometimes it confuses me and I feel like I have a big question mark stuck on my face when I overhear them talking.
I receive lots of sales solicitation calls at the office. I just can't believe what I'm hearing sometimes. They just can't greet their prospective clients properly and introduce themselves. Some of them try so hard to sound polite, but they sound insulting instead. As you might know, the Japanese language has 3 layers of politeness for verbs. Many of these young salespeople not only can't speak politely, they sound too casual. Just for kicks, I sometimes ask them questions about their service, and they can't answer. They're just lost and suddenly talking to me like they would talk to one of their friends. Only problem is: I don't want to make friends with them over the phone...
It's deplorable, today's crisis of slang, and it breaks my heart. This is not what I learned and studied in order to teach foreigners the Japanese language. "These days young people are..." is such a cliche, but it just keep popping up in my head.
Maybe I'm coming out the other side of the generation gap...!