Who said that?!

Reading an issue of Whoopee the other day, I noticed a mistake on the back cover. Not a small, easily overlooked mistake such as a spelling error or something, but a mistake with the speech bubbles! Sweeny Toddler was actually telling himself off, by saying what his dad was meant to be! Confusing I know, but I wonder how this was overlooked by the editor?

Here's the full story, illustrated by Tom Paterson.