I have been getting we were having a serious discussion rejection a lot. What would be a good come back from that, and how to really tell that if it was really a serious discussion or i am being dissed.

Either they are genuinely having a discussion, or it's a shit test - deal with it like it's a test either way. This has happened to me a few times before and it was always one of the girls speaking for the group... keep the mood light and use an FTC to disqualify yourself and she'll shut up. For example, "That's cool, I'm on my way back to my friends anyway but I wanted to stop for a second cos..." and continue from there. Shortly after this, it'll become clear if it was a shit test or not, that is unless she's in a bitchy mood of course and just wants rid of you.

The FTC should disarm her long enough to say what you wanna say but after that point, she may just try to get rid of you again. If she's polite about it, chances are you actually have walked in on a personal convo so your best bet is to be polite and eject, then you can come back later. If she keeps up the attitude however, pay attention to the rest of the group - if they like you, stay in set and tease her about how she's only pretending to be a bitch and how you don't fall for that one. Careful though, if she's actually in a bad mood and you're standing there making her friends laugh at her, she's gonna get nasty so if you're not too good at dealing with them when they get like this it'd be easier to just fire something direct in your targets ear and eject so she can come find you later.