From what I can tell it clearly appears when you press the enter button on the ComPostâ„¢, but there'll be a certain setup involving local51 being zero, local78 being truthy, and local77 being 7. So the next step is to find out what these locals are.
local77 is incremented when you press a button, and 7 is the amount of digits in the entity database ID codes. local78 is made true by Button::doVerb before incrementing local77, on a condition that involves [local69 local77] matching local79. If they don't match, 77 through 79 are reset (as also happens when the egg is triggered). Local69 is defined as [6 14 17 19 21 21 23], which is eight items for some reason, and is only used in that same part of Button::doVerb.
(if (== (= local79 (+ local79 value)) [local69 local77])
Value is of course the button's, so zero through nine.
It's obviously obscured so you can't just read the egg's database ID from the code.
6, 14-6=8, 17-8=9, 19-9=10, 21-10=11, 21-11=10, 23-10=13, so that's not quite it.
Still, perhaps this helps?