LOL, my sister's boyfriend did that once to me (as in, he called me on accident).  Fortunately is wasn't at a compromising time...he was just playing with their dogs...it was hilarious to listen to though.  I had to turn up the volume reallly high to hear them cuz the phone was in his pocket or on the table...I started screaming his name, but he couldn't hear me. 

  For some reason, after I hung up and called back, there was no answer...he must have had it on vibrate and had it on the table or something...but I do know it was him.