".@ErinAndrews should ask Richard Sherman why he stayed on the field while he's a physical liability," the "Arrow" actor tweeted about the ESPN interviewer Sunday after the Seattle Seahawks beat the Green Bay Packers.
Fair enough -- the Seahawks' Sherman had played lame for most of the second half of the game, obviously favoring his left arm after taking a hit to the elbow. Fans want to know the scoop, right? And Andrews, of all people, was in a position to ask the question.
Cassidy was among those fans, chiming in after her hunky costar with: "Seriously, why isn't she doing her job??"
Then Chrissy Teigen showed up, and it all hit the metaphorical fan. Teigen, of course, is buddies with Andrews.
The supermodel took a nasty shot at the "Arrow" ingenue: "JOB [noun] : the work a person does regularly to make money. alt: what @ErinAndrews has. 2nd alt: What you don't have. Bye!"
Guess Chrissy doesn't watch the CW? Last time we checked, Cassidy's Laurel Lynch was still alive on the superhero show.
Anyhoo, Cassidy almost took the high road, with a "God bless" response seemingly referring to the fact that Andrews was employed. Teigen took that as the actress "being holy." The "Arrow" star said she always had been, and welcomed Teigen "to the party."
"own it," Teigen taunted. "I'll take you seriously when you don't simultaneously talk [trash] and preach the gospel."
Wow, that escalated quickly?
Of course, "50 Shades of Grey" and "House of Cards" producer Dana Brunelli had to weigh in Monday, because Cassidy is his girlfriend.
"Since when is asking why someone isn't doing their job talking [trash]?" he wondered.
"since it's their ex's girlfriend," Teigen fired back.
Ouch. That's right. Cassidy dated Los Angeles Kings hunk Jarret Stoll briefly back in 2010, Us Weekly pointed out. And Stoll started dating Andrews two years later.
"correct... years ago," the actress noted. "Get over it because the rest of us are."
At that point Teigen shot a "God bless" back at Cassidy, earning herself a sarcastic shot-- "Awwwww you're sweet" -- from the actress, who added, "I'm sorry u have negativity inside u. Can't be healthy. 2 be clear, not [trash] talking. But interesting u took it that way."
After Teigen referred her back to that original tweet about Andrews, Cassidy continued with an explanation: "Most people wanted to know why Richard [Sherman] stayed in the game. He seemed like he was in pain, but I respect a big heart."
She couldn't let it go, however, without a parting shot at Teigen.
"Just to be clear, Your profile reads:"Gold digger and Stuff". You're asking me if I have a job? I'll send you a book," Cassidy tweeted. "For those of us who don't know Book(n) -a written/printed work consisting of pages glued or sewn together along one side and bound in covers."
Brunelli, for his part, kept peppering the Sports Illustrated model with questions.
"And being on a very popular series for the past 3 seasons is considered not having a job?," he said in a series of tweets that continued into Monday. "Chrissy, are you that butthurt over yesterday's loss?? Smile and move on. seems the only one talking [trash] here is you. And please explain to us all what your job is? Foot meet mouth."
Did we mention model Brooklyn Decker got into the scrum as well? Yeah, that happened. But it's too exhausting to explain.
Meanwhile, Amell -- the one who started it all -- wound up getting a personal response Monday from Andrews, addressing the seemingly innocent comment that set off the social media catfight.
"u get sports..," she wrote. "u know NO ONE was taking him [Sherman] out...how crazy GB didn't throw his way after the injury? Hope you & fam are well!"
"Arrow" returns to the CW on Wednesday night. We're guessing Teigen won't be tuning in.