I think the most confusing one is the usage of "I'll revert back" to mean "I'll get back to you". At least once in my life, I've seen an actual confusion caused by this. Here's how it went:

Let's call the two people involved Bob and Raj. Bob was working in the US and Raj was based in India. Bob emailed the team, addressing Raj, and said one of the attachments in a service needed to be deleted (I don't even remember why anymore).

Raj replied something along the lines of: "Yes, fine with me! Please delete and revert back."

Bob immediately replied, "Once the attachment is deleted, it's gone! It can't be reverted. Please confirm if you really want me to delete it."

It took a bit of back-and-forth before everyone was on the same page. What Raj had actually meant was simply, "Please delete it and get back to me."