Below is what I’ve summarized so far; if you have more, say so in the comments — this will be updated irregularly.
A commenter posted https://www.urbandictionary.com/ — a website recording all kinds of abbreviations. When you meet one you don’t know, just look it up directly. So convenient — turns out someone had already done it.
LGTM
Looks good to me
Often used when a colleague has reviewed your code and thinks it’s fine — they’ll say this.
IMHO
Often used to humbly offer an opinion, hoping the other side “won’t slap a smiling face”.
F2F
face to face
Often when chatting software isn’t satisfying enough and you want to talk in person.
AFAIK
As far as I know
Also a humble way of putting it.
RTFM
Read The Fucking Manual
Asking the other party to read the docs. Unless the question is really basic, not recommended.
STFW
Search The Fucking Web
Asking the other party to use a search engine — like RTFM above, use with caution.
ASAP
As soon as possible
If your boss says this, you should consider speeding up.
NSFW
Not safe for work (don’t open at work!!)
Some Reddit or other forum post titles contain this phrase, warning you that slacking off should have a bottom line — don’t open this post during work hours. If you open it without noticing, the gazes of surrounding colleagues may make you remember this word.
AITA
Am I The Asshole
Common in reddit relationship/gossip posts XD.