... maybe it's just my wishful thinking, but I'm interpreting that (given the next panel as well) as Asuka's sudden fish-slap to take charge. Obviously she wants more from Rei than Rei was intending.
Pursuant to above: Or maybe, given the crazy horny-Asuka with the long-ass Eel in the other pic uploaded with this one, it's maybe a literal fish-slap. Either way, it seems to be Asuka taking charge. I do wonder where the centipedes seem to have gone, though.
