I wanted to put the word "second" right in the headline so I wouldn't give the impression that this woman just flew off the handle and opened fire because McDonald's got her first burger order wrong. That would have been misleading.
The first bad burger did result in a complaint to the proprietor of the relevant McDonald's in Grand Rapids, Michigan (this happened in February—thanks, Elizabeth, for the reminder), but that dispute was resolved peacefully after the woman and her companion were told that they would receive a free meal at the time of their next visit.
That next visit, perhaps unwisely, took place at 3 a.m. the following morning after a night at the clubs. The same two women returned to the same restaurant, ordered the same burger from the drive-through window, and received the very same erroneous result as before. (The nature of this defect was not reported, but I assume it was something more serious than unwanted pickles, which you always seem to get but can just take off the burger, for Christ's sake). [Update: it was missing bacon, which, to be honest, does seem a lot worse.]
The woman in the passenger seat leaned over and delivered into the drive-through window first a verbal reprimand, and then one (1) 9mm bullet. The bullet traveled through the window, across the restaurant and out through the opposite wall, but luckily did not pass through any people on the way. The two women then fled.
But the shooter's previous demand for a free meal was her undoing. Turns out she had given her name and cell phone number to the restaurant the day before, apparently to verify her identity for free-meal purposes. Presumably she had forgotten about that at the time she opened fire.
So while the second bad burger triggered the violence, the first one ended up solving the crime.
The shooter was charged with three felonies and faced up to seven years in prison. The driver was not charged; police said they believed she had no idea her friend would try to shoot the drive-through worker, which seems like a reasonable assumption. And that was indeed the driver's story, as another report confirmed: "The driver of the car told 24 Hour News 8 Monday that she had no idea [her friend] had a gun. She also said she was having a difficult time hearing because her ears were ringing."
See also GRTK #23 (Canceled Taco Order) and #31 (Refused Second Pretzel Dip); also see also, e.g., "Man Demands Hot Sauce at Gunpoint" (Sept. 22, 2011), "'Burrito-Triggered Spree' Ends Peacefully After Three-Hour Standoff" (Mar. 24, 2011), and "Miami Shooting Reopens Debate Over Condiment Control" (May 29, 2007).