More than 20-some-odd years ago now...
I was working at KSMO... Santa Monica tower in southern California, as a pup controller. Lots and lots of primary students flying about. The departure end of the only runway, 21, is about a mile and a half from the ocean and pointing right at it.
One fine, sunny day, a student taxis out in a C152 for his first solo around the patch. I clear him for takeoff. He gets 3/4 of a mile or so upwind on departure, pointed out to sea, and calls me screaming, "Tower! The airplane won't turn left or right at all! What do I do?"
I think, "Crap. Next landfall is south of Melbourne. That's probably not going to work."
I'm at a loss, so I tell him, "Roger, make left traffic." Unbelievably, he says, "Roger" and promptly turns crosswind.
I sequence him and he lands safely. Not a thing wrong with the airframe either.
I've got other excellent stories, but thought I'd lead with that one...
Dave
PS I guess you asked for the "worst." That ain't it by a long shot.