1) You MUST have a jailbroken device.
2) Go into Cyida, if you already have xSellize, continue to step 4
3) Go into the place where you add repos (Cydia Sources)
4) Now once you've added it, go ahead and search : iap
5) There should be a few, depending on how many sources you have. There should be iapcracker and iapfree, you can check yourselves for the differences
6) Download either one, and launch an app. Note this will not work on online games such as Original Gangstaz and Global War etc.
7) Lets say you play Temple Run, you want more coins. Just go into the store and purchase it, it shouldn't ask you to login. You can spam the F**k out of it now
Enjoy don't forget to thank me for finding this awesome hack
HERES THE REPO/SOURCE https://cydia.xsellize.com/