How to Stay Anonymous While Using Metasploit?

Everyone always encourages you to use TOR and a VPN while doing illegal activities online, but how can you stay anonymous with that? For Metasploit, I port-forward so that the LHOST will work outside of my LAN, but what if the attacker is logged on to somebody else's network, and can't port-forward? I know this sounds kinda black-hat, but it's something I've been wondering about.

Thanks