[Gokudera is a little sad when he hears that. He'd really like to do this again. ...oh! But maybe Tsuna is talking about the dress when he says that?]

Yeah, you should have no problem taking it off now. [Wait, that sounds sort of...] I-I mean later! When you're ready to change back into your own clothes!

[He was definitely not imagining the Tenth getting undressed in front of him! It's just... after you spend so much time with Shamal, you become aware that so many things can have an alternate perverted meaning.]