Panel 1: As Elly puts her can-opener in the utility drawer, she wonders who could be ringing the doorbell at this time of day.
Panel 2: It turns out it's a delivery man; as he staggers under the weight of a Somy stereo, he says that there are a coupla large boxes here for Doctor Patterson.
Panel 3: As she reads the receipt, Elly reacts with hostility and disbelief; that's because he spent two thousand bucks on a stereo system.
Panel 4: She reacts to that knowledge by yelling "And I'm opening cans by hand!!!!!!!" The reason she does this is that she jumps to the faulty conclusion that his buying the sound system is an attempt to oppress her by forcing her to buy the manual opener she was so proud of buying just moments ago.
Summary: Let's see what's wrong with Elly's logic here; at no point in this story does John ever declare that she cannot have a new electric can opener despite Elly's clear belief otherwise. What John does eventually do is far "worse" in Elly's eyes; he reminds her that if she expresses a need, he will fulfill it immediately and thus rob her of a chance to be upset over nothing like the evil MAN he is. Also, she never seems to want to admit that she does not NEED to stint herself; doing without things one wants in order to pose as being humble strikes me as being hypocritical. It should also be noted that this is the minor irritation I call Phase One of the Foob Infidelity Cycle; her angry shrieking and refusal to allow John to make things right is Phase Two: "Appalling and Disproportionate Cruelty."