I saw three ex-students out-of-context in the span of three days and nailed all of their names:
1) saw a girl I had many, many years ago at a concert at The Saint in Asbury Park-- where her younger brother was playing drums in a band with one of my colleagues-- and though she is over thirty and has a kid and a house and a mortgage, she was far more surprised that I have kids and a house and a mortgage . . . "Mr. P. is all grown up!" was her reaction;
2) saw a dude I taught a few years ago stocking beer at the fancy beer store -- although I this one was a Texas-leaguer, as I only remembered his last name;
3) and, finally, an easy one . . . I saw a girl I taught last year lurking in the high school parking lot (there's nothing lamer than hanging around the high school once you've graduated, but -- to her credit -- I think she was waiting to give someone a ride).