She could explain to this math teacher that if he could count as well as Belichick, he might have a job that was more rewarding than having to be reduced to taking out his frustrations on his teenage students.
This right here.
You want to understand what motivates using the word "cheater" to a Patriots' fan. Now some of it is just good natured ribbing by people who know the idea of deflated footballs is a bit silly. But many people saying that to a Patriot fan is their attempt to lower your feeling of happiness over the Patriot success and/or bitterness from the underlying time/devotion they have to a sports team that is likely not even remotely as successful (imagine the devotion of a 16 game viewership devotion to a team like Cleveland? How they feel seeing the Patriots "them again!!!!" in the SB?).
Remember this, they win if you let your emotions get the better of you - you got knocked off your happiness -- win for them! They have succeeded if you don't maintain a jovial and philosophical stance.
Ultimately your goal is to take their serve and give it a solid return. Hit them back in their happiness and (important) ape the response over and over. "I realize you're bitter, jealous and unhappy because you've devoted so much time and effort to being a fan of a team that sucks. I guess I would be too if the team I spent so much time following sucked so bad too". Repeat, don't deviate it, repeat.
Next serve: "We'll least we don't cheat". Repeat above.
Next serve: "You have to cheat to win". Repeat above.
Repeat, repeat, repeat, repeat. If they ape it themselves then give it a primal showing of the back at the same time you repeat (walk away to a different task). Important, make sure you give no acknowledgement to their repeat as your are showing your back and walking away.
Now keep in mind if you do this successfully you likely create hostility. Someone being so emotional and trying hard to lessen your happiness may react belligerently when they see their investment in cutting you down not working (again consider the root cause of why they are doing it. Why? It's an ugly place that is impelling them to do it).
Side note: if you make the mistake of letting the conversation advance to facts, remember this person is coming from emotion and ignoance. You don;t win a conversation with someone like that you likely just end up at their plane/mindset (and they have won). Repeat "you are ignorant on the facts and it would take me just a few minutes on the Internet to show you you are ignorant of the facts" (the emotional person will typically spout gross inaccuracies easily refuted). They give back emotion and hysteria you give back "ignorant" and "the facts are right there in the computer". But again remember that when someone is blunted from trying to cut someone else's happiness down they can get belligerent. After repeating "you are ignorant on the facts and it would take me just a few minutes on the Internet to show you the facts" again give them the primal move of showing them your back and moving on to a different task or conversation with perfect no acknowledgement of anything they utter after you show your back.
No matter what they display from there on out you have 'chop chop' them in the same ugly place they started from.
Personally I think it's waste of time. Just make a smiling joke to the person "hey brother/friend/whomever, you really do prove ignorance is bliss", smile, show your back, move on without any further acknowledgement.
