maybe i am the only one who was interested in the many mysteries of the insta-hatch egg...
but after much research and experimentation, i have found the following things to be true about these impressive TS inventions...
they WILL retain their Insta-Hatchableness if you...
Place them in your home
Trade them with a friend
Deposit them into an SDB
they will NOT retain their Insta-Hatchableness if you...
Drop them anywhere
Give them to a friend
*Mix them up with "ordinary" eggs
*disputed twice; OP may have been drunk when she tried this. or maybe it was an insta-hatch mystery bug...