We've all seen My Fair Lady in which the rather pompous Professor Henry Higgins endeavors to make a silk purse out of a sow's ear through the meticulous teaching of proper grammar and pronunciation.
In this game, you are Prof. Higgins. If etiquette did not frown upon correcting grammar, non-existent words, and improper pronunciation, which are the examples you would correct most frequently?
For me it would be things like improper use of "I" and "me", as in "My dad took my brother and I to the zoo," which should be "My dad took my brother and me to the zoo."