caused by knowing too many people with the same name.
Bad part:  thinking my favorite paternal cousin was spontaneously getting married next summer even though it's wildly out of character and really a terrible idea (I was talking to his mom, hence associating the right name with the wrong person).
Good part:  the massive flood of relief that came when he responded to my frantic e-mail ("Your mom just said you're getting married.  WHAT!?  When?!  I want details.  Spill!") with a lot of laughter.
I thought I was going to have to talk that boy out of some pretty serious stuff.