Well... Humor is hard to translate, I hope it works out. I don't know if these jokes are all over the world, but they are pretty common here. (Turkiye) I beg your pardon if I waste your time by jokes you already knew.
So...
Anatomy proffessor is mad at the whole class during the final test. Vets take anatomy as a first year lesson but it's so hard that most fail, and must succeed the test in five years.
So many students fail that five classes are full of students, without any seat open. The Anatomy proffessor shakes his head. Angrily he speaks:
"I can't believe how incompetent you all are. If I tied a donkey to this class and explained anatmoy for five years, even it could pass!"
one of the students can't hold himself
"keep it tied for five more years and it becomes a proffessor."