I think I realize why I have love it so much when Tom mutes himself and talks over people, beyond it just being so funny. It's like being telepathically linked with someone for a brief time and getting to hear their mocking, critical, impromptu inner thoughts about another person. It's literally the ultimate inside joke. I don't want Tom to overkill it, but I'd love for him to do it more.
The "Help me!" story was one of the funniest things I've ever heard, but I have to admit that, if a friend did that in front of me, I might think they had some sort of deep psychological problems.