My family, of Polish descent, celebrates Easter as one of the big holiday of the year despite the fact that we are all atheists. A key element of our Easter tradition is to eat colored eggs, and to precede the meal with an egg-cracking competition. Each person takes and egg and pairs of people gently tap their eggs against one another. The first egg to crack loss and the winner compete with one another until only one egg survives.
Here are a few tips to competition-worth attractive and functional hard-boiled eggs.
The eggs should be hard-boiled. There are 3 ways to do this (in additional to crazy new-fangled approaches like steaming them).
1) If boiled water is used (as opposed to steaming), it means the eggs should be boiled for several minutes. If you start with cool water, put the eggs in, heat it fairly slowly, and then the eggs cool in the water, then the amount of time actually boiling is only a minute, but the cooling period in still-hot water needs to last 9 to 15 minutes (15 is for extra-large sized eggs). Putting the eggs in the water before it gets hot lets them warm more slowly and reduces the chance that they crack due to thermal expansion of the egg and the air cavity.
2) An alternative is to get the water boiling first, then lower the eggs into the hot water and let them boil briefly, and then let them cool in the water for the same length as time as above.
3) My own approach, however, is to put them in cool water as in method #1 above, let them boils for 7 minutes and then cool them rapidly in cold water which may allow them to peel more easily.
Despite years of speculation, we do not have a consensus yet on whether the pointy of the round end of the egg is stronger with respect to our competition. I am a pointy-person, but I have sometimes been beaten by a round-ender. It' hard to do any controlled study since every egg is different, but that makes the game more fun. ( Notably, there is real scientific analysis on idealized egg shapes that suggests the pointy end has greater rigidity and this should stand up better, but it might not apply to real eggs [see reference below].)
The Ph (acidity) of an egg apparently effects how easily it is peeled. Eggs what are more then 4 or 5 days old are more easily peeled after being cooked (they apparently have a Ph of over 92 which is the key value according to other sources). I don't know (yet) how this effects their robustness in the competition.
Egg shells are made primarily of calcium carbonate embedded in a protein substrate. The protein and an underlying collagen layer also help the egg hold together.
Boiled eggs go well with home-made horseradish. Making good strong horseradish is itself an interest undertaking. It is truly incomparable to the insipid store-bought stuff. Be prepared to cry -- a lot.
Egg-tapping and egg-cracking culture
Louisiana has a regulated egg knocking competition. According to this article, this custom is carried out in several Cajun communities throughout South Louisiana. In Marksville, there are cash prizes for the winner. The article suggests that some people believed that boiling the eggs in coffee grounds made them stronger. I've tried that and have not see a difference, but I wasn't rigorous.
Wikipedia this kind of contest is alternatively known as egg tapping, egg fighting, egg knocking, egg pacqueing, egg boxing, egg picking, or egg jarping, although no authorative source is given. It suggests the practice is or was popular in England as well as many other regions.
This reference suggests that some people think boiling the eggs in onion skins makes them stronger. I don't buy it.
Hard code shell science
The energy required for fracture of an egg shell for the narrow pole is greater than for the broad pole, but there might also be systematic differences in shell thickness as well as curvature.
The hen's egg: Relationship of mean strain energy at shell fracture to shell compression speed, the nature of the compressing body and the location on the shell of the point of contact (full article requires subscription or payment).