
Millie leaves to the right on the third panel but comes back from the left on the fourth. That's a visual media no-no.
As to joke, though, it's rather cute. I don't know if I'd like it if the joke just ended on "I get the hose", since that's making a none-too-subtle statement, but Ozy's little comment at the end is enough to remind you that they're children, and Millie probably just saw some stuff on TV and heard her mom extrapolating from there. Kind of like the 'pros and cons' strip, which is saved from mediocrity by Ozy's "We can run through the sprinkler" finisher.