That time again

So, at work, we have an account with the gas station right up the street. So, all of the work vehicles go there, get gas, and sign a slip. At the beginning of the month, I get a bill with a copy of all of the slips from the previous month. I also get a phone call reminder from the owner of this station.

One time when he called and asked if we could get a check to him by the end of the week, I replied with, "Oh yeah, it's that time again, huh?"

So now, everytime since then, when he calls...he says "It's that time again!"

Starting to get quite annoying. Maybe I should come up with something new for him to steal and say every month!!!