Here in Australia we have this comedy show which has just finished its
first season. It's called 'Thank God You're Here'.

Basically, they have four celebrity contestants, generally comedians or
radio stars. They are given a costume and then go on stage. From
their initial vantage point they cannot see the set.

When they open the door, a cast member greets them with the title
phrase. They must figure out who they're supposed to be and ad-lib
their way through the scene.

If this show gets picked up in the US, I can see Tara becoming one of
its most popular contestants.