For seniors with "low T" there is. NYLs (nubile young lovelies) only go for MYHs (muscular young hunks) and OWBs (old wrinkle bags) don't have what it takes to arouse the T we have left. There is another instance where SWF is used, the date want ads where categories are abbreviated, there it is Single White Female.

Joking aside and probably stating the obvious, where computers are concerned it stands for Shockwave Flash aka Adobe Flash. Due to obsolescence and security issues Mozilla dropped it in Firefox with the latest upgrade, in Add-ons Manager/Plugins, Shockwave Flash changed to an Ask to Activate - Never Activate option. They published a cutoff date when SWF will be dropped altogether, unfortunately I can't find it.