i can't take credit for all of these, some of my favorites:
talk is cheap, it takes money to buy whiskey
if your aunt had balls she would be your uncle
you can buy them books and you can buy them horses, and what do they do? they stand on the books and fcuk the horses
you can lead a horse to water, and sometimes he just sh#@s in the trough
I don't want your best effort, give me 100%
i am sure some of my grad students leave my office thinking i have lost my mind as drop these lines on them...especially the foreign students.