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)?
According to Harold Wentworth & Stuart Flexner, Dictionary of American Slang (1960), this usage of "something" in the United States goes back only to the early twentieth century:
Harold Wentworth, American Dialect Dictionary (1944) reports variants from roughly the same period using the regionalism suthin:
A far from thorough Google Books search finds numerous examples from the first decade of the twentieth century. From J.W. Moody, "My Quandary," in The Wood-worker (August 1903):
From E.S. Johnson, "The Age Limit," in The Atlantic Monthly (April 1904):
From Dorothy Richardson, The Long Day: The Story of a New York Working Girl (1905):
From Edith Nesbit, The Incomplete Amorist (1906):
From "A Crack-a-Jack New Year's Resolution," in Trade: A Journal for Retail Merchants (January 8, 1908):
From O. Henry, "The Count and the Wedding Guest," in The Trimmed Lamp, and Other Stories of the Four Million (1909):
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.