I use to travel by plane quite a bit.  On my way to my cheap business-section seat, as I walked though the First Class section I have passed Lyle Lovett, Wynona Judd and Jimmy Dean.  I did get to speak with the breakfast sausage baron and former singer briefly at the baggage carousel.  

I probably had the stupidest response in meeting a celebrity.  Was here in NW Montana, down on Flathead Lake 20 years ago.  Was inventorying utility stuff on roads.  I see this guy jogging.  He was huge and buffed.  He runs by and asks how we are doing, so we exchange good mornings.  On the way driving out, I catch up to him, slowed down, hung my head out the window, and said:  "Hey, you sure look like Howie Long".  He laughs, replies, "I hear that a lot".  Later I told somebody about that, and they said "Well, he lives down there".  

@bird72 I'm almost positive I met John Belushi in a bar waaaay back when.  Same line as you:  "are you John Belushi?"  "No, but I won a contest."  Still not sure ... never will know.  

Boy, oh boy, did I forget one.

I'm in my office at work where the break room doorway was maybe 20' from my office's doorway. There was an asbestos removal class going on in the break room for some of our maintenance employees. They were taking a class break so I went into refill my coffee. One of the employees in the class who knew how interested I've always been in music said you should meet the instructor.

It was Stanley Sheldon. Not only had he played extensively with Tommy Bolin but also had been a long time bassist for Peter Frampton, Stanley is on "Frampton Comes Alive," (and also played in the late 70's with Warren Zevon). After leaving the music industry he had gotten several masters degrees and was fluent in Spanish so he also did the training for those that didn't speak English. He was taken aback that someone was so familiar with his work, particularly the early times with Tommy. We became fast friends.

Not very long after that, Frampton rehired him for his band. Stanley probably played another five years with PF before stepping aside.

One of the other stories here jogged that memory, can't believe I didn't include it in the original post.