An interesting and clever example which shows just how scammers and fraudsters will go to get your one-time password or those 2 Factor Authentication codes to your bank accounts.

This example popped up here on Reddit. 

The person that received the text was tricked into sending the scammer the one-time passcode that they then used to seemingly used to fraudulent login to one of their accounts.

This goes to show you to never give out those codes to ANYONE, ever.  Not even to someone claiming to be from your bank through an unsolicited call to you.