(Strip Number 143, Original Publication Date, 16 June 1981)
Panel 1: We start off with Elly trying to walk down the street with Lizzie in tow; since it's become obvious that Mommy isn't going to carry her like always, Lizzie starts crying. Elly tells her "No. You're a big girl, Elizabeth; you can walk."
Panel 2: Since Lizzie doesn't really understand why Mommy wants to change things, she simply sits down on the sidewalk hoping that she'll get picked up; Elly responds by telling her "Bye-bye, then; Mommy's going."
Panel 3: We get to check "eyes narrowed in rage" off the bingo card as Elly walks down the street; the reason she's peeved is that Lizzie isn't taking the hint and walking like a big girl.
Panel 4: We next see a smiling Lizzie riding on Elly's back; Mommy's bug-eyed glare of existential horror is caused by her belief that Lizzie does this sort of stuff on purpose.
Summary: She isn't, of course, doing this to be mean, selfish and ruin Elly's day because she hates the idea of Mommy's being happy; Lynn will always believe otherwise but it's less about children getting their own way at parental expense and more about how they honestly don't know why Mommy's upset. Lizzie knows Elly's angry when she has to be carried but she doesn't know that it's because she's too heavy to carry; all she knows is that she is to be carried.