Symbolism, Imagery, Allegory
The egg cuber is another symbolic item in the breakup box. As its name suggests, this kitchen gadget makes a square egg. Its function? To force something eggs into a shape they're never naturally in—kind of like Min and Ed when it comes to dating each other. Min's an artsy kid, Ed's a jock, and according to the social laws of high school, these two don't really mix. And in the end, of course, no matter how Min tries to rearrange her life to make it fit with Ed's, it just doesn't; she can't stop him from cheating on her.
Ed buys seven egg cubers to make an elaborate recipe—"Greta's Cubed-Egg Igloo," to be precise—which shows him trying to meet Min where she is. Is he the sort to throw a birthday party for an old timey actress? Nope. But he humors Min, going all in on the party planning, as evidenced by his egg cuber purchase. No matter, though, because like we said: Eggs aren't supposed to be cubes, and Min and Ed aren't fated to be with each other.