In chapter 10, Spike finds out that Sapphire Shores wrote an overly sappy, sad song about him called “Full of Fire.” Spike’s initial reaction to this is, hiding himself under his wings forever to hide himself from embarrassment. But what really makes this so funny is Twilight and the others' reaction.
The chapter with the Gala includes Applejack and Rainbow singing the song. Very loudly. While completely pissed. The rest of their drunken arguments count as well.
When Spike is giving air-rides to some ponies, Scootaloo tell the passengers what the rules are. Needless to say hilarity ensues
Scootaloo: In case of emergency, don't – and I repeat don't – jump off Spike. We have a unicorn standing by if he hits a sudden downdraft or something…
Spike: I'm fine with downdrafts.
Scootaloo:…but she can't catch all of you and a dragon, so just stay put. Keep your seat-belt on at all times, and the pilot better not tell you to take it off, otherwise he's lookin' at a tail-kickin'."
Rainbow Dash: Sorry, Spike, you were cute (snickers)
Spike: Oh, shut up.
In the epilogue, Spike couldn't get through the courthouse door, and his hindquarters were left sticking outside for the whole of Canterlot to photograph.
It doesn't help that, Scoop Headlines had won his third Ponitzer Prize that year, with an article featuring a picture of Spike's scaly rump.
The author puts rather hilarious disclaimers at the start of the chapters. One example, from chapter 7:
My ponies! Muaahahah! Mine, all mine! M-my p-ponies! Mine? Please? Maybe one? Just one? Just a little one then? How about a background one? Aw dammit. Selfish Hasbro.
The Epilogue reveals that Twilight has spoken extensively with the Magician of Coal Crater, and was excited to learn that he is old enough to have personally met Starswirl the Bearded, one of her heroes. What the Magician has to say about Starswirl, however, is something of a disappointment for her… Particularly the parts about him having an impenetrable lisp, and wearing his famous bells because he was paranoid about insects stealing his clothes.
Applejack and Rainbow get drunk at the Gala. Every part of their antics is hilarious, from Pinkie's announcement of their states…
...to Rainbow bawling over how "awesome" Spike is…
Rainbow Dash: He's…so…grown-up...You are…you are, you're so awesome it totally and completely and totally and totally boggles my mind. You boggle. BOGGLE. Best dragon ever. Ever. You…you're the best…You're the besht.
…to Pinkie and Spike thinking up nicknames for their inebriated friends...
Pinkie: Oh, oh, oh, I know! We've got Rainbow Splash!