Every Starbucks employee's worst nightmare has come true for Brad Halsey, who shared his predicament in an email to the website Kitchenette for its "Horrible Restaurant Customers" series.

One of Halsey's most excruciating customers — let's call him "Mr. X" — is also the most brilliant. He figured out a way to game the Starbucks Card so he gets a free drink every day of his life.

As Halsey explains, Mr. X bought 365 Starbucks Cards and registered each one for a different birthday — so he gets a free birthday drink every day of the year.

"Even though I know exactly how he 'beat the system,' he pretends that his app is just malfunctioning and it magically gives him the same free birthday drink every day," Halsey wrote in the email to Kitchenette.

Not only does Mr. X get a free coffee every day, but he's particular about his order, the barista says. He orders his iced quad Venti vanilla white mocha with heavy cream instead of milk. So first, he asks Halsey for a venti cup and a marker.

Then he "draws lines and arrows and writes all over the cup," instructing Halsey to get his order perfectly jotted down as follows:

Two pumps of white mocha here, then add five pumps of vanilla. That should take us to this line here where you’re gonna add cold heavy cream up to this ridge here ... it should be halfway between this line and this line. Make sure to add the heavy whipping cream before the espresso; it changes the taste if you do it out of order. Then add your four shots — three regular and one long shot. That long shot is important, since you guys reformulated your machines, it’s been hell trying to get my drink right. That long shot helps balance it. Then stir it for me, Mister Brad. Now do me a favor and add ice to the top there and it’ll be easy as pie. I’m not picky so don’t worry about shaking it or anything like that.

In case you thought that was it, Mr. X then asks Halsey to ring it up as "one quad espresso, add white mocha, sub vanilla, sub heavy cream" so it's $3 instead of $6.50.