"I'm fairly certain you have to actually hold on to the bow to play your violin, miss."

"What? o_O"

Crotalus means that she is holding the bow wrong. She's holding on the strings of the bow.

Unsigned said:
Crotalus means that she is holding the bow wrong. She's holding on the strings of the bow.

And w00t is captioning her reaction to Crotalus's caption, hence the quote marks around each.

"...And RaisingK is further illuminating the scene with some well-placed exposition", gladwort says smartly, while self-narrating.

"Ojou-sama is going to get fingerprints on the horsehair, and rosin on your fingers", he says, directing his next comment inexplicably at the inanimate picture. "You must hold the bow by the frog."

"BakaHoushi said nothing of merit, but merely enjoyed the attention," he continued.

Or perhaps this girl is attempting to play the violin under the handicap of having no idea how to play the violin.