I once encountered a runner that tried to race me while I was walking.
I was just taking a stroll on a nice local trail that runs for a few miles alongside the river when I heard a runner coming behind me. The breathing was the first thing I heard, so I looked around and it was a guy in a generic racing singlet in his mid-20's (about my age) who looked fairly fit running about 6:30 pace. I turned and said "Way to go" to give him some encouragement since he seemed to be working fairly hard.
Well he evidently took my comment the wrong way and came to a stop right before he got to me. He said "You think you could ****** beat me, fat guy?"
I didn't know how to respond, here I was taking a walk in my tennis shoes and khaki shorts minding my own business when I've been challenged to a race by some anonymous runner. Also insulted, though I am by no means fat I don't run anymore and was a bit put off.
But of course what do I say, "I would kill you" forgetting that I can no longer run miles at sub-5:00 pace.
He says, still breathing a little hard, "Hah! Bring it."
I didn't feel like running at this point but he was really getting me worked up. After a few seconds hesitation I just took off down the path, and I could hear him follow behind. Well I didn't turn around for a while, I probably had put down a 2:10 800m, which gassed me, but I turned around and he was just a little speck down the path. I saw him turn around and start jogging the other way.
To this day, I consider this my last actual "race."