Yes there is that’s called account sharing, and if you get caught you will be actioned.
Anyway to the OP, they catch account sharing pretty quickly! They’ll see “Ughash logged in at Alabama 10 mins ago and now he’s in Vegas!”
Accounts usually lock down Incase of a compromise.
If you ever see anyone in chat confirming they’re account sharing, you can always take a screen shot and mail it to blizzard.