Changing Definitions

I was talking to a friend today at work. He's my age or maybe a little older.  He told me about his granddaughter.  She is 16.  She finished with high school early and is now attending college.  He tells me, "My granddaughter, she is 16 and going to college, she is hooking up with these college seniors.  They are showing her things and helping her out."  He looks at me with a big smile, like he is happy about it. 

I debate with myself.  Should I or shouldn't I?  He's a good guy.  I decide I should.  "Listen (insert name here), you may not know this but hooking up has a newer definition than it used to have.  I just think you ought to know." 

He looks at me.  "Really?  What is it?" 

I gulp and spit it out, "Sometimes hooking up refers to sexual behaviors."

He turns red.  "Really?"  Another coworker in the same room skedaddles out of the area after hearing me say this.  He calls after her to confirm what he has heard but she pretends she didn't hear him.  "I never heard of this.  When did this start?  I use hook up all the time.  I tell my friends we will hook up here and there.  What am I going to do?"

I say, "Be careful who you say it to."

"Seriously," he adds, "how long has this definition been going on?  Six months maybe?"

I tell him I'm not sure but I suspect it has been longer than six months.  Funny how definitions change over time.  How is a person supposed to keep up?  How does the average person know these things?  Hooking up used to mean meeting someone at a predetermined place and time or plugging a phone line into a wall or attaching a disabled car to a tow truck.  Hooking up used to be so innocent - just like the letter X.  The letter X was  naive and innocent until these movie ratings came along.  It was the only letter that could be the same on all four sides; a balanced and sturdy letter; and now it stands for perverted and pornographic.

What will be the next innocent word or letter to reference something sexual?  Wallpaper?  Telescope?  Calendar?  I hope someone sets me straight if I fall out of the loop and use unwittingly use a word with a newer definition.