When I was in college, and working as a temp in midtown over the summer, I would take lunches sometimes in the public space in the ground floor of the Philip Morris building. There was a gallery associated with some New York museum, I forget which, though I remember the Laurie Anderson retrospective that was hung there. The space also had a nice set of steps well-proportioned for sitting and reading, and tables where one could sit and eat. I think the space is still open to the public, although it's now the Altria Group building, you could go check it out for yourself.
Anyway, I worked a series of lame temp jobs in that general area, and would go there for lunch whenever I could, so I can't tell you exactly when this happened. But one day, my head was still half in the book I'd been reading as I walked towards the stairs and the door, and I didn't notice the guy sitting on the steps until I'd tripped over his foot.
"Oh!" I said when I recovered. "I'm --"
And then I stopped. Because I realized I'd tripped over Kurt Vonnegut.
Now, when you trip over some random man's foot in the lobby of the Philip Morris building, you don't expect it to be the author whose books you collected in a series of matched trade paperbacks through high school and into college. And when you're as lousy at face recognition as I am, you certainly don't expect to know that person on sight.
I was struck utterly dumb. He smiled, did one of those "don't worry about it" nod things, and I walked off on my way. I spent most of the rest of the day alternating between wishing I'd said something more and knowing that perhaps that wouldn't have been the right moment to say anything anyhow.
What strikes me now, mumblety-odd years on and not having thought of that story in years, is not just the sweetly New York oddity of authors being so thick on the ground that one is tripping over them, but how nice he was about the whole thing, the getting overlooked and then the starstruck silence. He was a mensch, take him all in all. I still have a couple of those trade paperbacks, too.