Luka generally takes all compliments towards the shape of his body with hostility/doubt. He doesn't really have a good understanding of what it means for something to be "sexy" and what people truly mean when they imply someone's like that. To him, being sexy is something that women are supposed to do. So he's adverse to the idea due to how he perceives it to be feminine. Though, I can generally see him acting a bit confused or less hostile to folks who pay attention to other parts of him. He likes having his stripes complimented though.