I think M is beginning to see Slightly Terrifying Giraffe for what he (she?) really is.*
*Do all giraffes have horns, or just the males? Ah, according to Wikipedia,** both sexes have horns, but the males have bald horns and the females tufty ones. The evidence of STG's horns is inconclusive.
**Also, I just typed "giraffe sex" into Google. Luckily, the search results page was not as frightening as one might imagine.