He concentrates on what Paul is doing, clinically, instead of looking directly at Paul or Kaworu or his own existential crisis. Paul is barely holding it together as it is, and one wrong look could deal the two of them irreparable psychic damage. (Kaworu is, apparently, immune.) The eggplant has Midoriya's full attention, because looking anywhere else guarantees he will die on the spot. Juices... And in nearly the same breath, Paul says his name like a dread summons.

"Probably shouldn't use your teeth to open it, but yeah... that's... yeah. Good. Great," he mumbles. Good. Great. Wonderful. He wishes Kaworu would stop waving the eggplant around, but, oddly, the ridiculousness of that makes all this a little less excruciating. It's... an eggplant. It looks stupid. He presses his lips tight on something that is not quite a laugh. It makes a strangled sound in his throat instead. He adds more clearly,

"They're single-use only. Put a new one on if you want to keep doing--eggplant stuff. If you two can find them all later, they're really better stored in their original packaging."

What do I... do now...? He didn't have a plan for how he would follow up this lesson and make it less awkward.

"Um..." he starts meekly, "breakfast's about ready. Just have to cook the omelette, but that takes no time. You should wash your hands and come down."

Or the earth could swallow him whole. That works too. He takes the eggplant from Kaworu. This is his mess, he's decided just now, so he'll clean this up.