Ha ha, Megan goes nuts when we fluff a trash bag as well, barks at any type of vacuuming, loves the hair dryer. What's really funny is she goes nuts when I get the tin foil out and tear a piece out!
Bailey barks at these things, too. Always, and loudly.
Other things Bailey barks at:
•other dogs, for real or on tv or on "sheltie tv" on the computer
•the bathroom door when I close it on her, and even when I get up and she knows I'm on the way to the bathroom
•the telephone--every time. She also barks when I'm about to end the conversation and hang up the phone.
•squirrels
•bicycles and kids, when they are cycling or walking past our living room window
•many times, as others have mentioned "just because".
Joey, on the other hand, rarely barks. Sometimes Bailey incites him to bark along with her, and he barks when Jim asks him if he wants to go out (like he's answering Jim with a "yes, yes") But mostly he's a (rare) quiet Sheltie.
They are as different as night and day!