Nah nah nah, specifically what did you do on there, and how that's somehow related to feminist propaganda.

Oh, and if I'm gonna derail I just I'll at least answer op's original question. Nothing serious is generally assumed until otherwise said, but it's generally implicit. Girls are fine saying they're just meeting up with guys for sex amongst friends, but wont react well to that being made explicit in a tinder chat or the first time you meet them. There's often no need to even bring it up. If they ask just say something like 'it depends, if I really click with someone I'm maybe open to more but for now I just want to take things easy and see how it goes.' Some shit like that, subcommunicates pretty much what you mean, but is nebulous enough that a girl doesn't have to openly accept a strangers offer to just fuck each other now and then.

In general though, clubs are a good shout if your goals just to get laid with a bunch of different girls.