Panel 1: Having accepted Liz's apology note and thanking her for it, Mrs Grunion gives her back her teddy bear and is about to do Elly's damned job by offering her some advice.
Panel 2: Said advice is not to do what people tell her to do but to only do the things she actually wants to do. As she says this, Christopher is looking on as if getting her into shit and seeing her lectured was the whole point of this mess.
Panel 3: He fucking proves it by laughing at her, the filthy little heathen. Realizing that he's a piece of shit who delights in the misery of others (in short, a larval John) leaves Liz looking horrified and sad.
Panel 4: We next see him getting whacked onna back of the head with the damned bear.
Summary: He'll probably get his arse in an uproar about having to pay for mouthing off but, hey, he should thank God that Liz didn't have a ceramic mug ready to hand. This is because the advice Mrs Grunion gave her is not quite to the point. What she should have been told is something direct like "Don't assault people just because you were dared or happen to feel like it" or "Your 'harmless' action could have gotten a lot of children hurt or killed, you idiot" instead of something vague she can take to mean anything she wants to. This inability to understand children eventually leads to us standing by a swollen stream watching a four year old half-way drown because Lynn and Elly are too stupid to understand what 'someone' means to a child.