randomly running into a friend on the street

actually, while crossing the street. ..so, in the middle of an intersection. and then you stand on the median with fast moving traffic on either side, talking about amusement parks for ten minutes.

and the sun is shining. and its a hot summer day. and you probably badly needed that lovely run-in today.

It's even better if you were coincidentally thinking of them, in a rather out-of-nowhere-fashion, earlier that day.