A word often used by a very enthusiastic teacher of a class who considers pop quizzes as opportunities, without feeling any mercy towards the poor children who will suffer under it.
Physics teacher: *claps hands* "TIME FOR A POPERTUNITY"
Student: "Screw you Mr. Elbaz"
Physics teacher: "what was that?"
Student: "Nothing.."
The chance to poop as loud as you want. It can refer to the moment when you are finally alone in a public restroom. It can also be used to refer to happening upon an outhouse on a hiking trip or a gas station on a road trip.
At the club, you see a fellow gay doing poppers, you walk up to her and say "poppertunity?"
If she is an self respectable gay, she'll gladly share her poppers.