The ultimate rock: The way I understand it, and solely based off idolm@ster's Tada Riina, "ROCKING", rather than hearing or playing or even dancing to Rock Music, stands for"rebelling against the stablished norm".
Hence, Koakuma's referring either to the opposition of norm or simply the subversion of the quiet library stereotype.
... "is the ultimate lock!"It's dead quiet inside.Well of course it'd be locked."A library that's noisy inside despite being soundproofed...Ah, this door is soundproof.Since she wanted to read in peace, she cast a soundproofing spell on it. Patchouli, I mean.That's right! Koakuma said this to me before!Heh? It's always so noisy inside, so I never noticed. Is there really even a point to it...?I never knew about it too....and by saying something so unintelligible, she made Patchouli snap.Ah♥ Not the base of my wings♥ It feels—Whose fault is it that it's so noisy in here!?I should be careful too.The base of the wings is tough for me, too.