Why so serious?

So around the end of May Dad was at his last day of work (he's a math teacher). In the afternoon he walks out to his truck, and this is what he sees. As you can imagine, he is stumped and confused. Nevertheless, he and his co-workers get a kick out of it. Turns out, they come up with this idea that one of the other math teacher's (who was getting married that month) classes meant to decorate HIS truck but mixed it up with my dad's. That afternoon Dad comes home and sits down by me. "Guess what?" he says. "What?" I say. And he proceeds to tell me the story of how his truck got decorated instead of his co-workers. Funny thing is, they didn't do it.
:D :D :D
My friend and I did it. (Let me clarify, though, I am NOT evil or smart enough to have thought of it. It was my friend's idea). So the next couple of months were ones of muffled laughter as we listened to Dad telling everyone about how "stupid high schoolers mixed up my truck with my co-worker's!".
This is where my mom becomes a criminal as well. It was her idea that we re-do it exactly the same on the first day of school this fall. So of course we did! Now it all would have been so perfect if there hadn't been one blunder. See, the poster we used that said "Just Married" was saved after the first time. Mom used it to make a poster for my birthday, and then I again snatched it in case we needed it again. So when we decided to re-do the truck, I re-used the poster. With my name on the back. I'm sure you can use your imagination to guess how events unfolded.
The funniest part about the second time around is that that afternoon my friend (the criminal) got a ride home with my dad. In the truck he decorated. As my dad puts it, it's like in all those shows where the murderer is the first person to go comfort the victim's family. So my friend rode all the way home as he listened to Dad trying to figure out who on earth could have decorated his truck AGAIN!
Thankfully it wasn't until that night that Dad actually noticed the back of the poster. And the rest is pretty much history. Let's just say there was a lot of shock, almost-screaming, and "You're lying!!" and "No way!!!!" happening that night. And of course Dad is on his pay-back streak. So don't be surprised if I don't post for a while...he might hijack my computer to play Miley Cyrus's "The Climb" every time I turn it on. Thus, I would never turn it on.