I don't get why, but it's an umbrella
A chimney.
an umbrella
Smoke
an umbrella
An umbrella.
Smoke
What may go down the chimney up but not down the chimney down?
An umbrella
An umbrella! It can go up a chimney when it's down because it's thin but cant go down a chimney up because its too big!
An umbrella !
An umbrella could.... but would? doubtful!
This sounds like the old riddle "What goes up a chimney down but can't go down a chimney up?" The answer is "an umbrella."