I find this highly entertaining. Yes, because I'm a nerd.

According to dictionary.com:

• "PS" means "phrase structure."
  
• "ps" stands for "picoseconds."
  
• "Ps." is an abbreviation for "Psalms."
• "ps." can be either "pieces" or "pseudonym."
• If you want to abbreviate "postscript," your only options are "P.S." and "p.s."
  
• (In case you're wondering what you might possibly be mistaken for, even though you're right, "P.S." can also stand for "passenger steamer," "permanent secretary," "Privy Seal," "prompt side" (theater) and "public school."

I'm just sayin', is all.

Aren't abbreviations fun? I love them.