Looking for a old exploit?

I tried searching for it, to no avail. can someone please link the exploit you could download, where you could purchase negative amounts of an item, and actually receive it, free? I want to try something with it (I know it can ban you, please don't reply that)

EDIT: It's NOT https://www.mpgh.net/forum/showthread.php?t=1235129

I remember an exploit with purchasing negative items, except it was to crash the server and dupe. And it was released to patch it, I think

It was an old dupe kushala daora released I think, I barely got uses out of it before it was banned. was a tradeable only dupe as I remember