If you have no clue of a topic in discussion, STAY HOME.
If you have an opinion on it, but don't know why, STAY HOME.
If you don't know any of the guys you can vote for, STAY HOME.
If the guy you want to vote for has a serious speech impediment and makes up new idioms, STAY HOME.
If you are Texan, please, please don't let your governor candidate for President by STAYing HOME.
If you don't know where any countries are and have a fairly good idea the guy you would vote for doesn't know any better, STAY HOME.
If you believe it is okay to invade other countries on the basis of dubious intelligence, please do the world a favor and STAY HOME and finish that Big Mac.
A toughy: If you cannot name all the states in 6 minutes, STAY HOME.
If everyone tells you to STAY HOME, find others who share that trait, form a militia and declare independence. No Taxation without Representation, remember?

edited to add: If you cannot write governor, STAY HOME.