This is like when the teacher wants you to "show proof" on your math test... Except the proof here is that they flipped the canvas occasionally while drawing.
You mean the picture that turns "I'd kill him for that" into "Don't make me kill you, brother?" You have an odd definition of what "stellar" means.
Actually, with the way she said it and her attitude below, I feel like "Don't make me kill you, brother?" is more correct, implying that him suggesting such things made her so embarrassed she wants to kill him to make him shut up. With the Japanese language being able to omit subjects, we really can't tell if she is saying "I'll kill (you)" or ""I'll kill (him)", so that hard translation is not incorrect by any means.