Well, not the easiest, but the best.
Well, not the best, but still a good one.

So tell me if you think it would work. It's probably possible though...

Requirements:
- A Jailbroken iPod Touch.
- The PayPal App
- Crackolous
- Installous

Okay, so upload the PayPal app to Installous by Cracking it via Crackulous.
Then delete the app from your iPod.
Now go into Installous and download the file you uploaded. (Dumb I know).
Don't install it, but you can if you want.

Now plug it into your computer and find your Installous Directory (somewhere in your iPod).
Find the .ipa that installs PayPal.
Edit it (I'm almost sure it's not packed) and make it e-mail you the E-Mail and Password in the textboxes when the log-in button is pressed.

Then upload the .ipa again to Installous.
Now anybody that downloads the app from your upload on Installous will be falling for a phishing scam.

So they log in and nothing looks wrong but you get their account.

inb4illegalisillegal