I actually got one of these codes from a local hotel person when I was trying to negotiate my own rate. When she gave me a rate I said:
"That won't be good enough."
"That's the best I can do."
"Well I guess I'll have to stay at X"
"You should use the XXXX code, it wil be $XXX, it's a better rate than I can give you."
"That will work!"
"Well you do work for XXXX don't you"
"Hey I've got an XXXXXX"
"There you go"
"Could you email that code to me?"
"Certainly"
"Thank you!"