Zoro is confident in saying that Sanji is a man who doesn’t do what he’s told. Which is why, when a command accidentally slips from Zoro’s lips during foreplay, he is expecting to hear the cook’s scoff as he continues to do what he pleases.

Three inches in front of Sanji's face, Zoro is wearing an expression that could wither stone. "What the fuck," the swordsman snarls, "do you think you’re doing." The remaining logical dregs of Sanji's brain recognize that he's just gotten himself into a pretty dicey situation. The rest of it apparently doesn't fucking care, though, because the absurd line of response he comes up with is to grin right in Zoro's supremely pissed-off face and say- "Well, what was your dumb ass doing?" In which the crew’s plastered, Zoro needs to blow off some steam, and Sanji gets taught a lesson or two.

There was a hook in the Cook’s galley floor. Zoro should've ignored it but it's not like he's all that good at keeping his mouth shut around Sanji.