Aussies are wide-brimmed (cowboy) style hats that are modeled after a hat whose look originated in the Australian military (slouch hat

Slouch hat

A slouch hat is a wide-brimmed felt or cloth hat with a chinstrap, most commonly worn as part of a military uniform. It is a survivor of the felt hats worn by certain 18th century armies. Since then, the slouch hat has been worn by military personnel from many nations including Australia, Britain,...

), giving the hat its name.
One of the common features in an "aussie" is the fold on either or both sides of the hat. The sides can be folded up, at an angle or enough to touch the dome of the hat. Often, the aussie is not completely flat. The hat arches from front to back and comes down behind the head. This hat style is favored by all types: sailor

Sailor

A sailor, mariner, or seaman is a person who navigates water-borne vessels or assists in their operation, maintenance, or service. The term can apply to professional mariners, military personnel, and recreational sailors as well as a plethora of other uses...

s, outdoorsmen, and the Cavaliers Drum and Bugle Corps

The Cavaliers Drum and Bugle Corps

The Cavaliers are a World Class drum and bugle corps based in Rosemont, Illinois and founded in 1948 by Donald Warren, and are a member corps of Drum Corps International, marching music's major league. The Cavaliers are currently under the direction of Adolph DeGrauwe...

, the Crossmen Drum and Bugle Corps

Crossmen Drum and Bugle Corps

The Crossmen are a World Class drum and bugle corps from San Antonio, Texas. Founded in 1975, they are a member of Drum Corps International. The Crossmen have had various geographic homes over the years, beginning in the southeastern Pennsylvania and Delaware Valley areas...

, Santa Clara Vanguard Drum and Bugle Corps

Santa Clara Vanguard Drum and Bugle Corps

Santa Clara Vanguard Drum and Bugle Corps is a World Class drum and bugle corps based in Santa Clara, California and founded in 1967, and is a member corps of Drum Corps International...

, and Reading Buccaneers Drum and Bugle Corps

Reading Buccaneers Drum and Bugle Corps

The Reading Buccaneers Drum and Bugle Corps is an all-age or senior drum and bugle corps based in Reading, Pennsylvania. The Buccaneers, also known by the nickname The Bucs, are charter members of Drum Corps Associates.-Pre-DCA :...

This expression is not used in Australia.