I've blown store bought hen eggs-- I used to start every year at the beginning of lent, and by eastertide, we had 2 or 3 dozen eggs to decorate, and hide (and it didn't matter much if you missed one, since they were just hollow shells.. so you could devise, and we did good hiding places. It didn't matter if you missed one, they were not going to rot or smell bad.
raw eggs and marrow, were considered old age food -- i guess because they are fat and nutrient rich. as for why you would suck eggs, If you are going to eat them raw, it does make sense to suck them from the egg shell, rather than break the shell..
i suppose, as well, if granny was sick in bed, and couldn't sit up, you could pierce the egg, make a small (drinking straw size) hole and an old person could just suck it out.
I think sucking eggs is like sylabubs.. (a drink made of milk, curdled with a sour juice (lemon), wine, and raw eggs.. Sounds horrid doesn't it? but everyone used to love them!) times change!
