In Ponyville...
Twilight and Spike entered the Castle of Friendship’s grand two-leaved gold doors, and into its hallways. Twilight stomped along with her brows furrowed, grumbling to herself.
“Come on, Twilight,” Spike pleaded, “the Apple family promised it wasn’t personal. After what Starlight did when she drank cider after a bad day, can you blame them for being...cautious?”
“I suppose not, but I’m Twilight, not Starlight. Am I the type of pony that’s super-prone to going a little crazy?”
“Uh–”
“I just heard myself, so don’t answer that. Still, after how much they laughed when we told them...what happened with the Princesses, Granny Smith could have at least given me one cup–”
One of the hallway’s doors opened in turquoise magic. The previously mentioned off-screen bad drunk, Starlight Glimmer, trotted through it. She stopped trotting and looked toward her friends, wearing a cheerful smile. “Oh, hey, guys. Where have you two been? You were gone when I got back.”
“We were sent on a friendship mission. Twilight could barely handle it, but I still don’t get why she was freaking out and sweating about it.”
“Maybe you’ll understand in a few years.” Twilight sighed, feeling her now-dry forehead with her hoof. “I probably lost 20% of my body weight from sweating, so about twenty pounds.”
After a chuckle, Spike said, “If it’s 20%, then it’s more like you lost thirty–”
Twilight glowered at Spike. “Spike, do you really want to go there with me in this bad a mood?”
“Okay, okay. Sorry.”
“I take it the mission was a rough one?” Starlight asked, her smile flipping into a concerned frown.
Twilight and Spike explained the insane events that occurred in Canterlot Castle.
After the story was over, Starlight’s eyelids twitched, her mouth quivering. The rest of her body stood still. Taking after her mentor, Starlight.exe had ceased working.
“Starlight? Are you okay?” Twilight asked, stress from her “friendship mission" ebbing.
Spike poked Starlight in her ribs. No response. “Uh, Twi? I think that story broke her.”
A curl crept on Starlight’s quivering lips. She collapsed to the floor, erupting in howling laughter.
“That is priceless! Oh, and Celestia asked if ‘it’ went in a mare’s mouth?! Ha ha ha! I wish the map had sent me with you!” Starlight’s eyes leaked tears from her raucous laughter. She mixed in rolls as she laughed, and laughed, and laughed.
Be honest: wouldn’t you be doing the same if you were in Starlight’s place?
“Yeah, it’s real hilarious,” Twilight said sarcastically. She stormed down the hallway and into her library, trailed by Spike.
After about a minute, Starlight’s laughter abruptly ended.
“Are you finally done laughing, Starlight?! It’s about time!” Twilight whined from a chair.
“...”
“Starlight?” Twilight asked again in a more concerned voice.
“...”
Something was amiss, so Twilight and Spike hurried out of the library and to where they had left Starlight. The duo’s mouths dropped.
On the floor, Starlight lay motionless on her side, eyes closed. A peaceful smile remained marked on her face.
“Starlight?!” Twilight and Spike shouted in unison. They dashed to Starlight, and Twilight shook her with her hooves.
“...”
“Starlight Glimmer, talk to us!” Twilight shook Starlight again, harder.
“...”
Spike felt Starlight’s neck. His eyes widened. “Twilight, I can’t feel a pulse! She actually died laughing!”
“What?!” Twilight felt Starlight’s neck, followed by her eyes joining Spike’s eyes in widening. “You’re right! Find some help, quick, and I’ll apply CPR!”
Spike bolted out of the castle; Twilight rolled Starlight onto her back and applied chest compressions.
“Starlight, you can’t die! You’re too young, and I still need a chance to laugh at you like you did at me!” Twilight switched chest compressions with mouth-to-mouth resuscitation.
After half a minute with no progress made, Twilight’s horn glowed magenta. A spark of electricity struck the dying unicorn.
Later, in the ICU of Ponyville’s Hospital...
“Twilight, I think she’s waking up!”
With a weak moan, Starlight pulled open her eyes. She was on her back in a hospital bed; Twilight and Spike stood beside Starlight’s bed. An oxygen mask covered Starlight's mouth and muzzle, and steady beeps from an EKG machine pulsed in the background.
“Oh...what happened?” Starlight started to roll toward the direction of her friends, but a stabbing pain in her chest stopped her movement and forced out a yelp.
“You died,” Spike answered nonchalantly.
“I what?!” Starlight shouted with her pupils shrinking to pinpricks, but she yelped from another stab of pain in her chest. “But I wasn’t ready to die! I still haven’t kissed...wait.” Starlight’s fear warped into confusion, allowing her pupils to regrow to normal size. “If I’m dead, how can I feel pain, and how can you see or hear me? Did I kill us by messing up spells, because I’m sorry if I did!”
“Don’t worry, Starlight. You’re still alive, and you didn’t kill anypony by messing up spells,” Twilight assured gently. “Plus, it’s not possible for you to accidentally kill anypony with spells.” She scraped the floor with a forehoof and continued, “After the third time I did it and Chrysalis revived us, I cast a worldwide spell to make all Equestrians immune to death by magical mishaps. It’s a long story, so don’t ask what happened.”
“Okay, but before I do it anyway and also ask how high was your body count, why did Spike say I died?”
Twilight answered, “Clinically, you did: you laughed so hard and long after hearing about our ‘friendship mission’, you suffocated yourself and your heart stopped.”
“But Twilight saved you by restarting your heart, but she broke four of your ribs by mistake while performing CPR on you.”
A grateful smile eased itself on Starlight’s lips. “Oh, thank you so much, Twilight, but what made me–” Starlight’s lips quivered. Another round of laughter followed, this time mired with the pain from her broken ribs. The beeping from the EKG picked up speed.
“Ow, oh I remember! Ha ha-ow! I’m so, so sorry–ow, and laughing is killing my chest, but–ow, that was just too funny!”
Twilight rolled her eyes. She took some solace in that both Starlight would be fine and that her laughing was painful, to Starlight. “Well, Spike, let’s tell the others that she’s going to be okay, given she doesn’t suffocate herself from laughing again.”
“Wait, Twilight, I just thought of something. It was your electric spell that restarted Starlight’s heart and only took you one try, right?”
She nodded. “That’s right.”
“Why didn’t you do that first instead of CPR? Did you forget?”
“No."
Spike scratched his head in bewilderment. “So why did you still do CPR? You wouldn’t have broken her ribs if you had given her heart a shock first.”
The alicorn scowled at the still-laughing and yelping Starlight, whose tears flowed down her face and oxygen mask as she laughed.
“Spike, I know.”