Mine is OOO for Out Of Office. I always misread it in my head like a ghost and it takes me a few seconds to process. It also doesn’t translate to speech—you have to say the whole thing.
Interested to see if others have similar acronyms they beef with.
WYSIWYG is also pretty common these days for tabletop gaming, with regard for models using the rules for whatever weapons or equipment they are actually holding. This came around as often people build the model one way (e.g. with a machine gun) before a rule change, after which they want to use the better rules without re-doing the model (e.g. with a flamethrower).