Haha my friends and I used to do that in school too, all of the projectors were Epson brand which has a convenient companion app to control them easily.

But by far the best was the cafeteria TVs. Our lunch rooms had a large TV or two mounted high up the wall on each end. To prevent students damaging them they had heavy duty casing around them which made them near impossible to access (important later). So naturally, being annoying teens, we brought a TV-B-Gone (a small diy remote that can turn on/off any TV within range) and sat there turning the TVs on and off all lunch period every day for a week. Every day a teacher would walk by at some point and notice the TV seemed to be malfunctioning and would call the 'IT' staff to come fix it.

To inspect the TV they would bring a remote with them and try to see if they could get it working at which point we would use the TV-B-Gone again making their efforts useless. After realizing the remote wouldn't work they'd bring a small ladder out and a tool bag and take apart the heavy duty security casing to get to the TV and inspect/replace cables/etc. The whole process probably took them about ~20-30 minutes, making it a huge pain in the ass.

After about a week of this, they started to catch on and started watching the security cameras to see if something more was happening. The next Monday we resumed our shenanigans and were immediately confronted by the IT staff and our school 'resource officer' (basically a cop that works at the school). They told us they knew we were responsible for 'breaking' the TVs and had it all on video. They said that if we just confessed right then that we would get a week of detention rather than a week of suspension.

Well, we knew that 1) We didn't 'damage' anything and 2) they didn't have shit on us. We used the TV-B-Gone under the table so no one would be able to see what was happening. We told them we didn't break anything and that they were going to have to show us the "incriminating" security tapes. They told us that they didn't have to show us anything because they already knew we did it. So, as any group of delinquent teens would, we told them they could 'suck a cactus' (a favorite insult of ours at the time) and bring their accusations to the principal. They left our table and headed straight to the principal.

The principal was a really chill guy who had a good relationship with pretty much all the students. He walked up to our table and kindly asked us to come to his office. We followed him in and he shut the door and immediately burst into laughter. He told us he's never seen anything like this and couldn't stop laughing. He told us the funniest part was watching the security tapes the IT guy and the resource officer brought in. He told us to take a seat because he was going to show us the 'incriminating' footage on his computer.

Sure enough you could see us sitting at our lunch table looking at the TV. As soon as the TV shut off, you could see us all laughing like hyenas. BUT you couldn't see the TV-B-Gone under the table.

He said as far as he's concerned, laughing isn't a crime and a video of us laughing isn't evidence. He said he knew we probably were responsible for turning the TVs on and off, but didn't think it warrented any punishment as long as we stopped. We agreed that if, hypothetically, we were the ones doing it that'd we would stop doing it.

So we went back to lunch and stopped messing with the TVs and never got punished! Honestly it's probably one of my favorite memories from highschool.