Panel 1: As they walk back from the corner store, Liz tells the Nichols boys that the last time Farley ran off, he ended up in the pound. What'll happen (to her) if he ends up getting scooped up by Animal Control again?
Panel 2: Richard (who doesn't actually care about what happens to Farley or Liz) asks her what happens if he got runned over while Christopher freaks her out by asking what happens if he got stolen. The reason Richard is mutilating English is the same reason Liz was depicted as calling Farley 'stoopid': they're created by a whining nitwit howling "Why aren't they born speaking English?" and who also probably forgot how old these kids are.
Panel 3: Since they're simply having fun winding up the Patterson girl 'cause it's amusing to watch her panic, Richard pushes Liz over the edge by telling her that if Farley got runned over and stoled, it'd be her fault. This horrifies her because not only is she directly responsible for Farley's loss, she's in the company of a boy who talks like a three year old just learning English despite being seven.
Panel 4: As Liz races off to find a place to hide from Elly's volcanic rages and refusal to forgive anyone anything because she's a deluded child who thinks that if she forgives anyone just the once, she'll be walked all over from then on, Chris yells "Okay, be like that....we were just trying to help!!"
Summary: I don't think that the Nichols boys have much of an idea of the Hell Liz thinks she's going to face when she gets home without the dog. I also don't think that they care. As for me, I'm starting to wonder what the Hell is wrong with Steve and Anne if they keep churning out mutants like Richard and Leah.