'Bunting tosser' or 'Bunts' is an informal term used in the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 to describe the sailors who hoist signal flags. Although dating from the period of signalling by flags

International maritime signal flags

The system of international maritime signal flags is one system of flag signals representing individual letters of the alphabet in signals to or from ships...

 , it has survived as a general term for naval signallers. Wireless operators may also be termed 'sparkers'.

Bunting

Bunting (textile)

Bunting was originally a specific type of lightweight worsted wool fabric generically known as tammy, manufactured from the turn of the 17th century, and used for making ribbons. and flags, including signal flags for the Royal Navy...

 is now a commonplace term for any small decorative flags or streamers strung on a line, but its original etymology is more specific as the worsted

Worsted

Worsted , is the name of a yarn, the cloth made from this yarn, and a yarn weight category. The name derives from the village of Worstead in the English county of Norfolk...

 cloth used for flags in the Navy.

The term doesn't appear in Covey Crump

Covey Crump

Commander A. Covey-Crump, Royal Navy , a former Naval Assistant to the Chief of Naval Information, was responsible in the mid-1950s for compiling a record of naval slang, abbreviations, legends and historical tid-bits. The first edition appeared on 17 May 1955...

, although that's a far from infallible source.

Although a naval term, 'bunting tosser' is known across the services and may be used as a jocular insult amongst Army signallers, the implication being that the person addressed is only fit for the Navy.