The phrase "unusual situation" means a circumstance or event that is not normal or typical. It refers to something out of the ordinary or unexpected. Full definition
He again shows his talent for interesting characters in unusual situations, and an extraordinary blend of black comedy, violence and personal struggles with morality. (moviereviewsfromthedark.com)
This way, a puppy will learn to keep its cool and not bite out of fear when it's confronted with unusual situations. (fox19.com)
So the older people are more protected than the younger ones, which is a very unusual situation. (scientificamerican.com)