I wanted to share an example I used to illustrate the concept:

M -> N and O

I imagined M being "meal", and N being "noodles" and "O" onions. It is necessary to have noodles and onions to make a tasty pasta meal.

Clearly, if you're out of noodles, you can't make pasta, and if you're out of onions, it might turn out rather flavourless (not a meal). This logic translates pretty cleanly into:

/N or /O -> /M

Let me know if this helped anyone else!

I imagined a dialogue to help me answer this question.

coach's team is loud and jeers at opponents when they win, parading about for a long time after the match has come to a close

Critic: Your team is a little too...enthusiastic when it comes to your wins. You're too loud and too mean to the opponents, and I feel like that's hurtful and unnecessary.

Coach: How dare you say my team is unprofessional! Say, even the top players are this loud and effusive! Let my players enjoy themselves!

Critic: Well, I didn't say you're unprofessional...just a little too much.