I need a nap something awful!
I know what this means, but I could never understand it: it's not easier to say, it's not more efficient, and it doesn't make sense! When was it started (and why)?
In The Tempest (3.1) Miranda says
This use of "something" seems to be softening the "wildly" - as in "a bit too wildly" rather than "incredibly wildly". That makes sense for the usual meaning of "something" being vague or undefined. Generally, "something awful" could mean "awful, in a way I can't quite describe."
But in your example, "something" is an intensifier - which is the complete opposite. It feels almost like the "something" is euphemistically substituting for a much stronger intensifier, like
and the vagueness is helping you avoid saying anything too rude.