An expression used in the académe industry which means , to have a terrible teaching method but is a good friend/mentor.

Usually applies to educators and professors.

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life

It is a type of teaching method that makes relatively easy concepts impossibly difficult and will make you realize that the only thing you will be able to learn is the fact that when tungsten is heated it lights up.