Carrot VS Stick

Hey people, share some experiences when you have used either the carrot or the stick or a combination of the two to influence your teammates to take a different course of action.

I want to learn how to herd sheep.

Example: I use the carrot to get people to upgrade their trinkets. I just casually mention, during a lull in battle, as if you're just making small talk and not trying to tell them what to do:

"Hey I just learned today that it's impossible to get an S+ rating without upgrading your trinket! Haha fucking rito."

Any other suggestions for how to get randoms in Summoner's Rift to change their behavior?

Reference material: https://en.wikipedia.org/wiki/Carrot_and_stick