Consider the two rings that this magician is holding in his hands:
How would you describe that configuration in topological terms?
From a knot-theory standpoint, I would say that the rings form a two-component link that is equivalent to a Hopf link. I'm no knot-theory specialist, though; they're may be a simpler way of putting it.
I'm wondering what technical term is used in topology to describe that type of relationship between such a pair of sets.