Lets see...

The huge fellow who practiced at 350% in class from warmup onward (directly caused by his badge & gun profession) and injured too many to name...

The young man who came through the door and having watched for all of an hour speaking with the head instructor proclaimed aloud "...that technique would never work... and he's doing it wrong..." He stayed for years afterward...

The angry little boy who refused to understand why we didn't get to the REAL jumping, flying, kicking techniques like on TV and spent all this time doing stupid boring drills...

The young boy who literally could not be silent for 60 seconds...ever! All kinds of techniques, all kinds of situations... techniques used to prevent it, not a single one ever worked.

There could be lots...
J