Abbreviations

General

ECF - E-Cigarette-Forum
Noob - Beginner
OP - Original Post(er)
Analog - Regular Cigarette
Mod - Homemade device/Moderator.
Pull - The act of sucking on the mouthpiece to pull the vapor into your mouth
TH - Throat Hit (The tingling sensation in the back of your throat)
Vapor - the “smoke” emitted from an e-cigarette
Vape, Vaping - The use of an e-cigarette (similar to the term “smoking” when referring to an analog)
Topping off - Adding drops of e-liquid to your current cartridge.
Dripping - Vaping by adding a few drops of e-liquid directly on the atomizer instead of using a cartridge.
Dipping - Sticking the bridge of the atomizer in e-liquid.

E-Cigarette

E-cig or E-cigarette - Electronic Cigarette
PV - Personal Vaporizer
Atty - Atomizer
Cart - Cartridge
Bat - Battery
Filler - The fiber found inside your cartridge that holds your e-liquid
PCC - Personal Charging Case
SD - ScrewDriver
JS - Janty Stick
PT - Passthrough or passthrough battery
2-piece/Disposable - 2 part e-cigarette. The Battery and a “cartomizer”.
Cartomizer - An atomizer built into the cartridge, marketed as disposable (you throw it away when the e-liquid is used up).
3-piece - 3 part e-cigarette. Battery, Atomizer, and Cartridge.
Cutoff - Refers to how long the battery will activate the atomizer before shutting down (safety measure to protect the atomizer).

E-Liquid

E-juice, e-liquid, juice - the liquid nicotine that you fill your cartridges with.
DIY - Do it yourself (homemade e-liquid mixture)
PG - Propylene Glycol
VG - Vegetable Glycerin(Glycerine = glycerin = vegetable glycerin(e) = glycerol)
PEG - Polylethylene Glycol

Suppliers

JC - Johnson Creek
PS - PureSmoker
TW - Totally Wicked
EST - E-smokeytreats
JS - JantyStick
SD - ScrewDriver
GG - The GG!

Miscellaneous 

FDA - Food and Drug Administration
ECA - Electronic Cigarette Association
NRT - Nicotine Replacement Therapy (patch, gum)
PH - Public Health
BP - Big Pharmaceutical Companies
BT - Big Tobacco Companies
ALF - American Legacy Foundation
‘Anti’s - Anti-smoking people who do not acknowledge that vaping is a viable alternative to smoking analogs.
RYO - Roll your own (tobacco)
THR - tobacco harm reduction: the use of tobacco products that are safer than smoking; the removal of smoke from tobacco use. Examples: Snus, e-cigarettes. Ways to continue use of tobacco or nicotine without smoke, with a huge reduction in risk of 99% or more.

Universal Forum Lingo

AFAIK - As Far As I Know
BTW - By The Way
DOA - Dead On Arrival (didn’t work from the moment I got it)
FWIW- For What It’s Worth
FYI - For Your Information
IDK - I Don’t Know
IIRC - If I Recall/Remember Correctly
IMO or IMHO - In My Opinion or In My Humble Opinion (some mean ‘H’ to be Honest)
IOW - In Other Words
JK or JJ - Just Kidding or Just Joking
OMG or OMFG - Oh My God and its adult extension
PITA - Pain In The Ass
PWN - Own or “dominate”
ROTFLOL - Rolling On The Floor Laughing Out Loud
ROTFLMFAO - ^ Adult Extension of above
SOL - (can’t be helped or fixed)
(SP?) - Used when unsure of the spelling of the previous word
TIA - Thanks In Advance
TMI - Too Much Information (too personal)
TLDR - too long, didn’t read
TOS - Terms Of Service (“the rules”)
TROLL - A person that posts in a forum/thread with the sole intention of provoking an argument (can sometimes also imply a “spy”)
TY - Thank You
WOOT - Exclamation, as in Hooray! (Sometimes: Want One Of Those)
WTF - Same As below
WTH - What/Where/Who The Hell
YMMV - Your Mileage May Vary (your experience may differ from mine)