Jesse Spencer Did Something Hilariously NSFW After That Chicago Fire Proposal Scene

Chicago Fire Season 11 ended on a romantic cliffhanger: with Casey (Jesse Spencer) proposing to Brett (Kara Killmer). 

"Sylvie Brett, we were meant to be," he says in the episode, arriving at Brett's doorstep and getting down on one knee. "Will you make me and the three kids the luckiest family in the world? Marry me." (The children he's referencing, of course, are  Andrew Darden's two sons, whom Casey has been raising in Oregon, and the little girl Brett just found out she's adopting.)  

The scene ends before we find out Brett's answer, and the air is thick with anticipation. When the director yelled, "Cut!" though, Spencer and Killmer were total goofballs. In fact, Spencer did something very funny (and a little NSFW) once the scene was over to break all that romantic-character tension. And thankfully, Killmer got it all on tape. 

Here's what happened: 

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Jesse Spencer's hilarious NSFW stunt after filming that proposal scene on Chicago Fire

Brett (Kara Killmer) and Casey (Jesse Spencer) shown on Season 11 Episode 18 of Chicago Fire. Photo: George Burns Jr./NBC

"Rehearsal of 'the scene' from the Season 11 finale, filmed by our illustrious director, Reza Tabrizi, framed by our lovely D.P., @civilwill," Killmer captioned the video that showed behind-the-scenes footage from the moment Casey proposed. "I asked Jesse not to show me the ring until we were actually filming so I could be surprised. Obviously there were some fun reactions from the peanut gallery.🤡"

One "fun reaction from the peanut gallery" that Killmer's referring to was when someone off-camera joked that Brett should "say no" to Casey's proposal. To this, Spencer hilariously flipped the bird to the commenter in question, prompting laughs from everyone on set. How cheeky!

Watch for yourself, below: 

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Of course, Casey's return for two episodes in Season 11 has fans wondering if the character will be back on Chicago Fire full-time in the future. Spencer told NBC Insider about this, "The idea when I left the show was that if it was appropriate and it would work with the storyline they wanted to do, I would be open — and they would be open — to bringing Casey back. The storyline [in Episode 18] does allude to Casey sort of eyeing whether he could actually move back to 51. Can he potentially, in the future, rekindle his relationship with Brett [Kara Killmer] and start that fire again? We’re 'gonna have to see. Casey’s looking at it; it’s a potential thing, but we just don’t know right now. We’ll leave that to the future. We’ll throw it to the gods and see what they say."