Celebrity Power & how would I act if I met one?

I have an intrest in reading about the lives of celebrities. Actually I shouldn't say that I'm really all that intrested in their lives per se, more like the gossip about their lives. I don't think I could really put my finger on what has lead me to develop this intrest. What it basically boils down to is that I find the life of a celebrity to be so very fundamentally different from my own life that they fascinate me. Take Paris Hilton for example. I'd image that she is extremely self-centered and shallow. Basically uneducated about the troubles and strife of the common man. However she is filthy rich and ridiculously famous. And does she use her power for good or evil? All I see is her hopping from one rich playboy to the next. I admire nothing about her. However her fashion choices amaze me at times.
Another fascinating celebrity is Angelina Jolie. She is drop dead gorgeous and is known for her global intrest in the welfare of children. She has adopted a little girl, whom she rescued from the brink of death. Angelina has announced a desire to adopt other children. The woman seems to be using her celebrity power for good.
Anyway, the point of this pointless rant was that at times an odd question will insanely pop into my head: How would I act if I were to meet a celebrity? Granted this little part of the world is unlikely to draw anyone of significance but I can only wonder. If I were to be in line at the grocery store and I suddenly looked over to unmistakeably recognize Brad Pitt, what would I do? A sophisticated, intelligent part of me (small though it may be) hopes that I might be able to quietly say hello and smile at him knowingly without causing any unwanted attention to be drawn to him. Another, less sophisticated part of me (larger though it may be) thinks I might loudly say to anyone around that, "Hey ya'll that's Brad Pitt!!!" Oh well, I really don't know what I'd do. The bets are on that I'll never find out. Seriously, aren't celebrities just people too? I wonder sometimes.