a fastie

A trick or deception. Typically used in the phrase "pull a fastie." Primarily heard in Australia. It turns out that the supposed alien visitors that people had been seeing were just a bunch of teenagers pulling a fastie on the town. The fake article had been in print in the renowned scientific journal for more than a week before its author revealed that he had pulled a fastie. I've got a great plan to pull a fastie on the school for April Fools' Day.

pull a fastie (on someone)

To carry out a trick, deception, or practical joke (against someone). Primarily heard in Australia. It turns out that the supposed alien visitors that people had been seeing were just a bunch of teenagers pulling a fastie on the town. The fake article had been in print in the renowned scientific journal for more than a week before its author revealed that he had pulled a fastie.