When I was a kid, I was playing Beyond Zork, and one night when I was very tired I came across a pterodactyl. Unfortunately, I kept making typos.

>> aim wand at perodactyl

> I see no perodactyl here.

>> aim wand at pterodacyl

> I see no pterodacyl here.

Frustrated at my continuing mistakes, I decided to try to short-circuit their logic. Despite knowing the difference, I typed this:

> aim wand at bird

And the game replied:

> a pterodactyl is not a bird