Friday evening, I rode down 30 floors in an hotel elevator with James Carville. The elevator dinged, the door opened, I stepped on, glanced at the other passenger, said “Good evening, Mr. Carville,” and we dropped like a rock to the lobby. I don’t think he was in town for Comic-Con. 
So what other random encounters have other Dopers had? Tell me about your wierd and wonderful “ships that pass in the night.”
I always get him and Story Musgrave mixed up.
Does Scott Hamilton live in Charleston SC? I think I passed him on the sidewalk one day.
Uh, I saw you speak at graduation a few weeks ago. Does that count?
No?
Ok, then. Pat Benatar. That woman is SMALL. Met her in an elevator in Palm Springs. Would have been an entertaining meeting if this fucking hurricane of a cow that I was with hadn’t made a drunken ass out of herself by falling all over tiny little Pat.
I once went to a music fair and went to the signing tent to meet Sonia of Disappear Fear. Later on, driving home, me and my friend stopped at Burger King. Sonia was in line, recognized me, and gave me a big hug. 
When I was in high school I used to work at a small Mom and Pop store in Jupiter, FL. We had celebrities who had summer homes who would occassionally come in:
Joe Namath, who I did not even recognize b/c he’s so damn skinny now.
Burt Reynolds, who is surprisingly quiet. Instead of renting movies he’d ask to buy them outright as we was not sure if he could get them back.
I have a bunch.
I saw GWB walk by once. I was up on a balcony so I couldn’t say “What in the holy name of fu…”, er, “hello.”
I almost bumped into Mike Wallace on Martha’s Vineyard.
When I worked as a movie theatre cashier, the police called me to tell me to let Mayor Flynn in for free. I didn’t recognize him, so I charged him full price. Then we ran out of seats, so we had to put him in the aisle on a chair from the office. Oh, and the air conditioner broke, too.
I sat next to John Lithgow in a Pizzeria Uno.
I’ve played video games with someone who’s performing in Farm Aid.
So. . .she hit her with her best shot, huh?
I live in NYC, so I have bumped into all sorts of odd celebrities.
I brushed past a guy a narrow sidewalk smoking with his buddies. Since he was blocking the damn sidewalk, I probably muttered something pretty rude. Apparently it was Russell Crowe.
A better experience was running into the dude who played Samir from Office Space. I had never approached an actor I recognized because usually I don’t care, but I was going through some weird stuff at the time and I wanted to show my appreciation for a movie I really enjoy. I think we ended up drinking and talking for an hour or so. He appreciated the fact that I even knew who he was.
In Vegas I ate at the buffet at the Golden Nugget and then later rode in an elevator with Troy Polamalu. He was very polite.
I saw Senator Lincoln Chaffee getting his own soda at a McDonald’s Express in the Arcade in downtown Providence.
My mom and I were touring the White House, walked through a door and almost bumped into a guy, then realized it was George H. W. Bush. The man in front of him, one President Reagan, turned, realized we were “friendlies” and smiled just as a couple of Service guys politely but quickly ushered us to the side of a stage where we watched a press conference unfold.
At Barton Springs just a year or so after her performance Mary Lou Retton and her date had the recliners next to us.
When some autograph hounds approached the guy seated in front of me at the boxing match during the Atlanta Olympics, I realized it was Butterbean. We’d taken a “Sponsor” bus there and I’d had a nice chat with hair dude Paul Mitchell.
I was peeing at the Peabody when I noticed it was Robert Duvall squirtin’ next to me.
Leaving a BBQ joint in Ft. Worth I walked past someone who looked kinda familiar, then realized it was Dicky Betts.
Walking out of an Atlanta Hotel, we ran into Bob Hope and gave him a round of polite applause. He stood at his limo door, smiled and really seemed very touched.
I used to bag Doc Watsons groceries when I lived in Boone.
I’ve sold a camera battery (when I worked at the Radio Shack in Lowell MA) to Michael Chiklis. I asked if he was the guy from “The Commish”, which he was. This was WAY before The Shield & Fantastic 4 days.
Martin Sheen came out of the West Wing set and biked passed us with a jolly “Hello.” one day when I was doing some IT work on the WB lots in LA.
I’m personally proud that I fawned over neither, and simply recognized who they were, and said “hello” back.
*The * Doc Watson? The blind guitar master? That’s super cool.
Back when I lived in NYC, I encountered more celebrities than I remember.
I was once shopping for towels in Bloomingdale’s, and so was Barbra Streisand. She was comparing two towels, so I casually told her to get the pink ones. She thanked me.
My then-bf took me to a party, where I was introduced to Stephen Sondheim, Mandy Patinkin, Chita Rivera and Kitty Carlisle.
I saw Jackie and Carolyn Kennedy, I think on the day JFK Jr. got his law degree.
I used to shop at the same grocery store as Allen Ginsburg; saw him there all the time.
And many, many more … Leonard Bernstein, Woody Allen, Ed Koch, Sly Stallone, Geraldo Rivera, Keith Haring, Phil Donahue & Marlo Thomas, etc., etc., etc.
I didn’t know who he was the first few times. He and his wife were very nice. Everybody would say, “Hey Doc!” as they were coming and going.
I walked out for lunch last week, and the Obama Get Out The Vote bus was on the plaza. There was a white man giving a political speech, and I said to my companion, “That looks like Howard Dean.”
Two blocks later, we walked past the Obama HQ and there was a sign that said, ‘See Howard Dean at noon.’
Jodi Picoult and I were at the same showing of Mamma Mia the other night. I felt bad because I had just been thinking negatively about Nineteen Minutes.
Oh sweet cheezus, no. Although, I wish Ms. Benatar had hit the cow. It would have been satisfying. This was, I dunno, maybe eight years ago? I still cringe when I think back to that night…having shown up to this place with someone who acted like that. It was appalling. Benatar got on the elevator, and my, ahem “acquaintance” being just sober enough to recognize who just got on the elevator, and way too far past tanked to control herself (all 5’9" and 250 or so pounds of her) starts slobbering over this tiny person and touching her and telling her in slurred speech just what a big fan she is. I just wanted to crawl into the carpet. That evening did not end well. shudder
ETA: Apparently, Hell Isn’t just For Children anymore.
My husband and I sauntered into the student lounge at his law school and almost ran right into Tommy Lasorda.
I mentioned in another thread already, but a few weeks ago I went to a matinee screening of Hellboy II. When we exited the theater, we were behind an old man who had clearly been military and still looked like he could kick someone’s ass. R. Lee Ermey is a local here, so I wasn’t too surprised.
Husband had a few encounters at the Wooden Center at UCLA: a game of basketball with Adam Sandler, and a few weeks ago he saw Peter Weller in the weight room (trying to look low key and reading a book on Leo III in between sets).