We had a scrimmage the other night involving our public middle school boys team and the nearby boys CYO team. Each league has different rules for defense: Public School conference requires man-to-man whereas CYO allows man-to-man or zone.
The coaches got together beforehand and the CYO coach said he'd play man to man with a zone press after made baskets. No problem there.
At start of one of the quarters, I give to ball to Green (our team) for a throw in and as Green is setting up for their offense, I notice White in a 2-3 zone.
So, I wait three seconds, and whistle their center for an illegal defense since he was in the lane for 3 seconds without guarding anyone.
Every adult sitting in the stands (not that many, luckily) was in shock. And I then found out from my friend (the public MS coach) that he wanted the white (home) team to play zone this quarter.
After mentally hiding under a rock for a moment, I gave the ball back to green on the side and continued play from there.
And unrelated to the above, but on the topic of T's, I once saw a coach get 5 technical fouls in one dead ball when I was in grade school. One for a sub that ran onto the floor straight from the bench and then 4 more for arguing about it with the referees. (Of course, back then Ts were only one shot in NFHS).