A sig line is what you put after or below your nick/name at the end of an email or posted message. It can be any number of things but usually is a humorous or pithy quotation, or a link to one's webpage. It should be no more than one or two lines long.

SIG Sauer pistols are undoubtedly the finest TDA .45s and 9mms in the world.

When a beginner spams their signature move a lot, It is also very annoying sig spamming sucks.

On a community forum, placing a bet with another forum member where the agreement is that the loser has to accept the profile signature provided by the winning party.

also a nickname for Phi Sigma Kappa. Whichever organization was at the school first usually lays claim to this. An alternate term can be PSK or Phi Sig Kap if Phi Sigma Sigma was there first.

Sigma Fag Prepsalon - the "largest" fraternity in the nation which any jackass can join, cut them a check, sign on the line, and walk through the magic door of bullshit all in the same weekend. Whether they're known for being a bunch of pussy's or serving their famous roofie-colada punch at their parties, they're never known for anything good.

One Gallon of Arnold Palmer half lemonade and half sweet tea mixed with half fifth of everclear.

Invented by the Theta Chapter of Sigma Tau Gamma