basically means that you're friends, but both of you know that there's a possibility of you becoming an item in the future.
julia: we decided on being fwp, so we'll see where it goes from there
Crazy white people who perform hairbrained stunts to impress people, usually frat guys or dropouts. See Jackass
Glen: I don't know, what?
Truman: Dude! Check this shit out!