I can't break eggs cleanly; always end up with some mess outside the pan and/or some eggshell shards in the food.
That's annoying, and maybe one day some genetics wiz might find a way to preprogram a break line into chicken eggs. Maybe. (BTW, the German Sollbruchstelle sounds better and more precise)
Why do I bother with undead not-even-proto-chickens? The last four weeks I've had loads of them, in a (successful) attempt at a low-carb diet (Quite easy in a country like this were meat is good and cheap). This is to get my waistline back in shape and the weight down by a few kilos.
After some startup time it has worked fine, I'm down about 6 kgs (now at 83, 186cm and genetically not meant to look slim) and the flotation ring around the hips is mostly gone. That's the same weight I had a good 12 years ago, and I'm happy.
I've also changed my eating habits substantially, and that way the weight level should be ok to hold. My dad might be proud that his (then un-appreciated) admonitions work Just Fine -- with a delay of almost 30 years: when we were small, he tended to gruffly remind us to chew every bite 30+ times and to put the fork down between bites. My sisters and I were never badly wolfing down our food, but still he felt that he had to rebuke us gruffly. Didn't work then, works fine now.