We'll see Elly's angry reaction tomorrow. Right now, he's channeling Gene Kelly.
Panels 1-4: He splashes around in some puddles. Lynn 'helpfully' reminds us that he's doing so by filing the panels with lame-ass and unnecessary onomatopoeia.
Panel 5: He proves himself to not have been paying attention by thinking to himself that Elly will approve of what he's doing because he's playing and washing his feet at the same time.
Summary: Imagine his shock when he finds out that Elly was serious about his not getting wet. Imagine the look of consternation on John's face when he's told to punish the boy because he didn't realize his mother was a nutjob who asks the impossible.