Knowing Aviation people, it also could be a Zap. (6094 could be right, also)
A Zap is done without the squadron's knowledge, and if it is painted on like that, it is done with a touch of respect for the unit you are zapping. When zapping, you are careful to use a mask and a good can of paint, you want your mark to look good enough that the zappee might consider keeping it on their aircraft.
The land bases type is usually done by grabbing one of your unit's stencils, but, in this case, it looks exactly like the right shape to be an Australian Insignia Roo stencil.
Aboard a ship, the Zap is more often some graffiti, which usually had to be washed off by the pilot, this type of zap was usually earned by landing on the "wrong" carrier for some reason.
Zaps didn't have to be unit badges or white graffiti, though. VMFA-115 Silver Eagles picked up a pair of Boondockers painted on Eagle feet on their tail badges,,,,,,,,by some VMFA-314 ground crew. (one of which served his next deployment with -115, lol. Makes for an "interesting" photo in an old Gunny's cruise book collection. (sorry, forgot the part where this happened in the Vietnam era, and both were Phantom squadrons at the time)