There is a principle of improv that says in order to draw an audience
into the drama, each actor must take a "yes, and" approach. If one
actor says that it is a cold day and shivers, then all the other actors
must join in and build on that to create a realistic scene,
collaboratively, on-the-fly. In short, it leads to better performances.
"Accepting an offer is usually accompanied by adding a new offer, often
building on the earlier one; this is a process improvisers refer to as "Yes,
And..." and is considered the
cornerstone of improvisational
technique. Every new piece of information added helps the improvisers
to refine their characters and progress the action of the scene."
Wikipedia - Improvisational Theatre