Actually it means, Standard Operating Procedure

Standing Operating Procedure (SOP) - Commonly and erroneously referred to as Standard Operating Procedure. Written military directives defining the actions to be taken upon the occurance of specific events.

Standard Operating Procedure. Things that are routine and come naturally to a person. Commonly pronounced as "soppy"

Someone who is soppy: overly emotional, overly romantic, and generally being a wuss. You wouldn't call yourself a sop, you'd call someone who wasn't being hard enough one. Commonly used in the UK.

to soak up gravy or other liquid like foods with bread or other material

Acronym for Sudden Onset Painful Shits. Occurs at random, often in the middle of the night, and can have multiple bouts in one occurrence.

Homer Simpson's misspelling of the word 'stop'.

In the Simpsons Movie, when Homer located the truck in which his family was being held, he made an attempt to hold the truck off for a moment, using a red hexagon (as opposed to an octagon) with the word 'SOP' sloppily painted on it. But as with almost anything that Homer does, it actually worked.