Beofre we get into the tutorial on how to jailbreak some things should be checked about your device.
1. An iPod touch 3G must have been purchased after september 22nd 2009
2. A iPod touch 3G only came in 32gb and 64gb
If you bought (what you thought was a 3G) a 8GB or 16gb “3G” It is technically an iPod touch 2g with a new bootrom to patch the exploit with jailbreaks.
With that said one last check to see if you have a 3G is if you have multitasking, voice control, and home screen wallpaper without a jailbreak.
To jailbreak your 3G on 4.2.1 you can use Redsn0w 0.9.6 beta 6
