Those who are addicted to messaging and emailing will find this list comprehensive and useful...

O: Opponent

OAO: Over And Out

OAUS: On An Unrelated Subject

OBE: Overcome By Events

OBTW: Oh By The Way

OBX: Old Battle Axe

OC: Original Character -or- Own Character

OCD: Obsessive Compulsive Disorder

ODTAA: One Damn Thing After Another

OIC: Oh, I See

OICU812: Oh I See, You Ate One Too

OK: All Correct

OL: Old Lady

OLL: Online Love

OLN: Online Netiquette

OM: Old Man

OMB: Oh My Buddha

OMDB: Over My Dead Body

OMFG: Oh My F***ing God

OMG: Oh My God

OMIK: Open Mouth, Insert Keyboard

OML: Oh My Lord

ONID: Oh No I Didn't

ONNA: Oh No, Not Again

ONNTA: Oh No, Not This Again

ONUD: Oh No You Didn't -or- Oh No You Don't

OOAK: One Of A Kind

OOC: Out Of Character -or- Out Of Control

OOF: Out Of Facility

OOI: Out Of Interest

OOO: Out Of Office

OOTB: Out Of The Box -or- Out Of The Blue

OOTC: Obligatory On Topic Comment

OSIF: Oh Sh** I Forgot

OSINTOT: Oh Sh** I Never Thought Of That

OT: Off Topic

OTASOIC: Owing To A Slight Oversight In Construction

OTC: Over The Counter

OTF: Off The Floor -or- On The phone (Fone)

OTH: Off The Hook

OTL: Out To Lunch

OTOH: On The Other Hand

OTP: On The Phone

OTT: Over The Top

OTTOMH: Off The Top Of My Head

OTW: Off The Wall

OUSU: Oh, You Shut Up

OWTTE: Or Words To That Effect

OZ: Australia

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