What is "flirtatious banter"?

Hi all! -sorry in advance for the length-
So this will be my first time posting, and it's come to this because I can't take my lovely friends' advice.
I work at a fast food joint and one too many times a few of my managers seem to comment on my apparent "flirtatious" nature towards the guys at work, myself being a girl, but the most recent caught my attention and now I need to know whats up.

Although, when I look at the situations myself, I have the same kinds of conversations with my female and male co workers, im just a- for lack of perfect wording- playful (?) person. I joke around a lot, just in general conversation, I don't like to take things too seriously because life's too short you know? So if boys are being boys and say a jokingly flirty line (my friend called it "flirtatious banter" if that makes any sense) I tend to brush it off in a joking manner as well because im just a little immature to take guys seriously right now. Im 17 (going on 18), and a lot of people see that as the perfect age to whisk yourself into a teen romance, but i haven't figured out how to do that yet, so im just trying to be positive with everything else in my life.
The way I deal with the guys at work is how I deal with everyone, maybe its just too friendly? Like theres sexual jokes thrown around, but thats just the kind of immature conversation people my age, whom are mostly the people i work with, have- right? Then theres jokes thrown around about me being one of the guy's girlfriend, that we just joke around with being like "oh yeah, we've been dating for 5 years now" etc etc, like it's all taken so light heartedly and everyone, including the managers, knows that- they just call it out rather than join in. Its a fast food joint so its a very relaxed atmosphere in general and everyones really friendly with each other, I just don't know why im such an outlier.

Anyways, with that background, a recent matter kinda irked (?) me a little, if thats the right word.
Pretty much theres a guy that I get along with well, except he's 9 years older. Only reason we get along is because he's very immature for his age. He's still a man and I still recognise him as older than me, except he acts as if he's like 20, when he's in fact 26. A couple days ago, at one of my last shifts a recently new manager was listening to our "flirtatious banter" and then said "Wow, Im feeling a lot of sexual tension between the two of you." which both of us looked confused by that statement, but we kinda just joked along with it saying stuff like "oh yeah, so much tension, so much" etc etc but then on my break, me and this guy were talking and the same manager was walking towards where we were sitting talking to the rest of the crew. We could hear her coming and then she said "I'm fully expecting to walk in on them going at it in the crew room".
Again we kinda just looked at each other confused, then she arrived to where we were and said "hey, why aren't you guys on top of each other?" and I don't really know why she was being so forward with the situation? We were honestly just talking, and yeah we do talk a lot, but there's never anything remotely sexual- and if there is its always an obvious joke, just like with everyone else.

I told my friend, pretty much everything above, and she insists that because she knows me and sees the way I behave around everyone and that im just a playful personality and the new manager just doesn't get that yet. But I just don't understand why my conversations, or just me interacting with the guys at work, is flirtatious. I know when I flirt, I know how to flirt, and I don't do it at work, but why would my new manager pick it out like that?

To me flirtatious banter is just harmless flirting, I mean it's not like you are trying to seduce bfs away from gfs with your actions, right. If the managers think it is too much maybe some people complained and maybe keep it on the download while at work so you don't lose your job over it. Sounds like these boys and men are doing it to you also, people talking to them too? if not why did you get a talk to is what I would ask. Bit of a double standard happening at your work place that if it was me I'd address. Just don't engage in any flirty talk in the work premises, if they start up at you, smile and walk away and do your work.

Thats just the thing though, I don't know what i'm doing to come off as "flirtatious" so im not entirely sure how to tone it down without blatantly ignoring my friends. From my perspective its all just joking around and no one in the workplace takes any of it seriously, it was just that most recent comment from the new manager that struck my attention because she blew it so far out of proportion.
And, there aren't any complaints about my behaviour, more just teasing my obliviousness to this "flirtatious behaviour" but there are definitely double standards. I have heard one of my male co workers- that i purposely stay away from- pretty much harass a female co worker for sexual attention of sorts, and he has never been called out on it. Yes the girl mentioned is very self sufficient and stood up for herself, but it is still something that should be more on topic rather than my friendships with male staff.
Im sort of just stuck, and im also tired of suddenly having to worry about everything I say or do whenever I talk to male co workers. Even if there are stupid, harmless sexual innuendoes or jokes thrown around, I feel because of my gender it wont ever be taken for what it is; 'friendly banter', rather always 'flirtatious banter'.

Life gives us all hard knocks. :'(

This new manager is very unprofessional. It's sexual harassment, and you can report her. If she has an issue with this workplace sexual banter, then she should be privately discussing her concerns with you both privately. She is totally out of line.

I totally get, when you work with people for awhile, you get comfortable with each other. The dirty jokes, sexual innuendo, teasing, bantering, harmless flirting is a normal part of the work environment. BTW it's common at all ages...a lot of whom I work with are i their 40's and 50's and we do the same thing. As you get older you will realize we never truly grow up.

Anywho, this manager is probably shocked at how you all talk to each other, and doesn't know what to make of it. So she ya she could be either be trying to fit in, or it's her passive aggressive way to deal with it by making those comments. Either way don't take it personally. If you don't want to report her, then I suggest you simply kool it or tone it down when she's around.