Not to deliver it, but to take the package or envelope, check the address, then put it in a pile to go to a distribution center in the appropriate, proximal zip code of its destination. That done, the mail might wait up to a day to be flown out, two days at times, then another day to be delivered by ground.
Some breeds of dogs have a natural curl or bend to their tails. But others have been selectively bred to take this curl to an extreme, cork-screw shape. Dog breeds with curly tails referred to as screw tails include Boston Terriers, Pugs, Bulldogs and French Bulldogs.
Twizzle stick is a variant of swizzle stick (aka, really thin little straw that you get in mixed drinks), and seems to be more common in British English. Some dogs, especially Labrador retrievers, have twizzles at the end of their tails: As one guide describes it: Many Labs develop a twizzle at the end of their tails at around 4 or 5 months. A Lab's thick coat wraps itself around the tail, and an inch or so will continue off the end in a twist of hair. Twizzle wire is a kind of wire used in making bracelets. It looks somewhat like a spring.