Fallout and chill is sort of like Netflix and chill, only better. You start off by your boyfriend/girlfriend playing Fallout, and you are kind of just there as a third wheel. Then, you start taking off all your clothes, but your partner is still too focused on killing
Rad roaches. After you are completely naked, your partner will eventually notice and will start to take off their clothes too, then you guys fuck while your partner is STILL FUCKING PLAYING FALLOUT AND NOT PAYING ATTENTION TO YOU WHATSOEVER, and it is just really great! :)
Ross: I am so going to Fallout and chill later with Jessica.
Ryan: Niiiiiiiccceeee
Actual chilling while playing Fallout. Rarely ends with sex depending on the interest of the person not playing.
Girl: Fallout and chill?
Guy: Sure.
Girl: Wanna fuck?
Guy: Another settlement needs my help.