> I guess some people feel all "leet" by using abbreviations without (or before) defining them and expecting everyone else to run around looking them up.

> It's tired and lame.

It's an incredibly common term we use at my workplace, and I expect many other engineering orgs use it as well.

We use it not only for services ("five nines"), but also for tasks and human initiated things.

It's a simple and useful stand-in for a complicated and abstract concept. I don't expect to have to explain SLAs every time they are discussed.