Stands for First Outer Inner Last
A math acronym used for multiplying binomials.
This is known to the world as the best math operation known to man. It is by far the most useful, this is a scientifically proven FACT and should not be disputed by anyone, ever. Doing so is punishable by death.
Courtney - "Did you hear the Bobby does not like to FOIL?"
Abbey - "He should be killed, because that is punishable by death..."