The Marauders explaining their nickname to a random student at school;
"Why do you call him that?" A fellow Gryffindor asked one day.
Peter whipped around to appraise the little first year, before responding, "Call him what?" Clearly stalling for time.
"Moony," the kid responded like he thought Peter was being daft, "I don't get the joke."
"That's his rabbits name," James said loudly, a grin beginning to play across his face, "he's got this silver rabbit at home, and Remus named him Moony. He's quite the furry little problem."
Remus smacked his head on the table, but the kid shrugged, clearly appeased by this answer, and turned to walk off. Remus glanced back up to see his friends shaking with laughter as he hissed, "A rabbit? That's the best you could come up with!"
"I was put on the spot," James defended, almost unintelligible from his shaking voice.
"Last week you came up with an essay worth of excuses why it wasn't you who turned Slughorn's mustache blue, and now you get stumped!"
His friends were no longer listening, they were still too busy laughing.
"So what should I say next time someone asks me why I call you Prongs?" He deflected. "His head's so big he needs the antlers for support?"
They didn't even seem to hear him, and his three friends were promptly kicked out of the library by Madam Pince for making too much noise.
This one is probably the epitome of pointless since Remus explained clearly what he was talking about, but I wrote it down anyway, so I hope you enjoyed it anyways.