"Um, Spike, you're a baby dragon. Even when mired in rampant greediness, I can't imagine dragons reaching sexual maturity for several decades. Are you sure you understand how arousal actually works?"
"What? Yeah, come on Fluttershy, of course I do! It's when your uh"--he blushed while deciding upon an appropriate term-- "tinkler gets all hard and tingly and you just wanna--"
"Oh my! Okay Spike, I see you are familiar with masturbation. Um... how did you learn all this... that is, if you don't um, mind?"
"Well, one day I asked Twilight about these strange urges I was getting, and she told me alllll about these things. She even included diagrams!"
"Oh my!" Fluttershy repeated, blushing furiously at the thought of Twilight clinically describing the birds and the bees to her younger brother/son/friend/servant thing.
"So yeah, that's my story," said Spike. "So can you uhhhhh, you know, do the thing we talked about?"
If Fluttershy was blushing before, she was straight up really blushing now. "I... do I have to? Aren't you, um, a bit young for this... fetish?"
"Awww come on Fluttershy," Spike pleaded. "Do it for a friend. Pleeeaaase?"
"Well, I guess if it makes you happy..."