Yes, the prank is:
3 whistles that all make the same 3 sounds and none of those sounds are anywhere close to a professional cat caller.
The developer says this much in the application description.
Still, knowing that 90% of the human population is too lazy to actually read descriptions, the title should have been something different or at least contained the words THIS IS NOT A REAL CAT WHISTLE in giant bold letters.
Then again, knowing about that 90% laziness factor, I’m sure this review will never be read.