This clause is appropriate when speaking of "knowing" a certain individual. I'll have you know, that it's usually the most used clause considering I live in Las Vegas - the land of the fakes. I can think of twenty million stories of where this clause applies. So for our first (and most used) clause, try #47 on your friends when you're talking about really "knowing" someone through and through.
Person 1: Dude, did you know _____ used to sleep with all of her old bosses? She got the job by sleeping with _____ and she sleeps with _____ just to keep her job!
Tyler: No way, she's not even like that! I've known that girl for 1.5 years, but there is always Clause #47...
Just sayin' -T