Thanks to official Friend of ORCA™, Niall, ORCA has hit the Biostar forum. Quite a few of the suggested acronyms in the thread are already queued up for (re)posting but check out Niall's post for an earlier look at some of the riches the field of bioinformatics provides in terms of contrived acronyms - good and bad!
Biostar administrator Istvan Albert contributed one for Biostar itself: BIOinformatic Special Tactics And Rescue. I don't think Biostar is actually an acronym in reality. (Although I always thought it was BioStars and was short for Bioinformatics Stars!) This might constitute a new class of acronym - one that is made up after the word has already been in existence for a while. Inverted post hoc, maybe.
I am guessing that Istvan was inspired by SWAT - Special Weapons And Tactics - a classic that probably deserves a place in ORCA itself. I reckon SWAT is also post hoc - they go and swat the bad guys but it's a tenuous link at best.
PS. If you like this sort of thing, you should also check out another Biostars forum post, CRAC: funny and/or weird names for bioinformatics tools.