This is how a prank too far goes in 28 Train-Pranks Later.
[The ponies and engines go to talk to Percy]
Thomas: Percy! We need your help.
Percy: Okay. What for?
James: Are you honestly going to stand there and tell us you know nothing about all the pranking Gordon has been doing?
Rarity: Because he's gone too far this time.
[Percy gives a puzzled look]
Percy: Oh, no! He's been pranking up a storm!
Pinkie Pie: Well, I didn't find his last prank funny.
Henry: Me too. So, does our friends.
Fluttershy: Did he get you, too?
Percy: [laughs] Oh, yeah! He and Gummy both!
Percy: Aaah! [giggling]
Percy: They got me good.
Twilight Sparkle: Really?
Toby: Well, he needs to stop.
Percy: Stop? But pranks are so much fun!
Thomas: Not for everybody. And it doesn't seem like Gordon is taking the time to find out who enjoys them and who doesn't.
All but Thomas: [grumble]
James: Uh, since you and Gordon share such an, uh, affinity for pranking, we thought you might be able to get him to, um, uh... quit it!
Percy: Hey, Gordon! I have something very important to tell you!
Gordon: Percy, hey! I actually have something totally important to tell you!
Percy: You do? Ooh! You go first!
Gordon: Okay, you know how I've been pranking everybody?
Percy: Yeah! [giggles] It's been pretty funny! I-I-I mean, actually, that's what I have to talk to you about.
Gordon: Here. Have some Emergon.
Percy: Ooh! Thanks! [glugs]
Gordon: So, I got to thinking – why waste my time pranking everybody one at a time when I could prank everybody at once?
Percy: Mmm, wow! Everybody at once?! That sounds amazing!
[record needle scratches]
Percy: Gah, wait! I mean, it's not.
Gordon: You don't even know what it is yet! Percy, this is gonna be the best prank ever! I special ordered these joke Energon cubes so the colors would match my paintwork.
Gordon: And I'm going to replace the Energon cubes at the Filly Guide Energon and Cookie Drive for joke Energon and everyone who drinks it gets an Energon covered mouth courtesy of Gordon! Ha-ha! It's gonna be so awesome!
Percy: Uh, I don't know. I mean, it doesn't really seem all that funny.
Gordon: [gasps] What!?
Percy: Maybe this is a good time to stop pranking for a while. The other ponies and engines in Equesodor really—
Gordon: Stop?! No way, Jose. This prank is happening, Percy! And it's gonna be hilarious!
[Later, Gordon goes to visit Percy at Sugarcube Corner]
Gordon: Percy, what's the deal? I told you I needed your help switching out all the Filly Guide Energon for the joke Energon. But when you didn't show, I had to do it all by myself! Uh, Percy?
[He sees Pinkie tending to Percy]
Pinkie Pie: Hi, Gordon. Percy's sick, that's why he didn't show. So I'm taking care of him.
Gordon: [chuckles] Wow. [to Percy] Your mouth is still pretty Energoned.
Percy: Yeah. [coughs] I haven't really [coughs] been feeling well. And this joke Energon is the only thing that makes me feel better. You don't have any more, do you?!
Gordon: Uh, no. I just told you, I used it all for the prank.
Gordon: Pretty soon, the CMCs will start selling it to everybody on the island. Ponies and Engines will open their boxes and start eating, then all of their teeth will turn Energon-coloured, and they'll know it was me! It's gonna be so awesome! C'mon, you don't wanna miss it!
Percy: Actually... [coughs] I don't think I can even... puff... an... inch... [raspy] Unless you've got more Energon!
Gordon: Uh, on second thoughts, you should stay here and rest.
Percy: [sighs] Yeah. You're right. Sorry to miss out. I'm sure it's gonna be hilarious.
Pinkie Pie: I'll get you more Energon, Percy. [goes off to do so]