One of several identical candies chosen at the start of play to be poisonous.

Suppose we want to give the player a bag of candies, of which a random one is poisonous. We can pick which one should be poisoned at the start of play, like this:

"Candy"
The plural of piece of candy is pieces of candy. A piece of candy is a kind of thing. A piece of candy is always edible. Four pieces of candy are in the Halloween bag.
Toxicity is a kind of value. The toxicities are safe and poisonous. A piece of candy has a toxicity. A piece of candy is usually safe.
The Porch is a room. The player carries the Halloween bag.
After eating a poisonous piece of candy:
   say "Oh, that didn't taste right at all. Oh well!"
When play begins:
   now a random piece of candy is poisonous.
Test me with "eat candy / g / g / g".
Test me with "eat candy / g / g / g".
Porch

>(Testing.)

>[1] eat candy
(first taking the piece of candy)
Oh, that didn't taste right at all. Oh well!

>[2] g
(first taking the piece of candy)
You eat the piece of candy. Not bad.

>[3] g
(first taking the piece of candy)
You eat the piece of candy. Not bad.

>[4] g
(first taking the piece of candy)
You eat the piece of candy. Not bad.