Is it possible to put money into someone's bank account with out them knowing you did it?
Yes. You only need their account number (in most banks)
No unless they never check their bank
Yes, you tell someone that you're going to put money in their account. They'll be happy to let you do so.
Why thank you, Lt; What a pleasant surprise!
You can put money into anyone's account without knowing their account number. Hey, tell your family & friends they're welcomed to deposit into mine anytime.
Maybe in cash! Not sure. Checks and money orders can be looked up.
Only if you have their account number