Used during a time of aggression when something doesn't go according to plan, not actually as a command.
The abbreviation is generally used so parental figures don't know wtf you're saying.
Person 2: Yeah...FMS.
Something you say when you just hate your school
a: i know right?
A condition where one is always on the lookout for the next cool thing, rather than enjoying what one has, because he/she is "afraid of missing something."
When people behave unexplainably bizzarely due to a full moon! Much more common than is recognised.
Wife: Oh my god what is wrong with me? Thanks luv
Husband: You best take the day off it looks like you have come down with a bad dose of FMS!