FOMO is an acronym for "Fear of Missing Out", the anxiety that arises at missed opportunities. FOMO is not the desire to do something, but is rather the aversion to the aftereffects of not doing something. Its not that you want to go to the party, its that you don't want to be spending Monday morning hearing your friends talk about the party, and feeling regret. Like so much else, FOMO is a phenomenon of social media, where platforms like Facebook and Instagram make events seem more attractive and fun than they are. After all, one smiling group pose of people on a trip can make someone forget that the people probably had to be trapped in a car for hours, had to wait in line, had to pay a lot of money, and might not have really been having too much fun.
FOMO is an unavoidable feeling, so much that it is sometimes hard for us to remember what we want to do, and not what we don't want to not have done.