Say what? the OP said they wanted it to work like red envelopes where you double click on the item and it increases your zeny (or errors and doesn't proceed if it'd put you over 2.147b). And its obtained by talking to an NPC with menus that eats your zeny then spawns an item in your inventory.
What I don't get is why you're more interested in finding ways this can't work than finding ways it can work without causing problems.
Edited by Kadelia, 01 March 2016 - 06:14 PM.