Oklahoma Indian (and a three-word description of this puzzle's theme)

Question:

Answer:

OTOE

Length:

Similar Crossword Questions:

Like this answer, or a two-word description of this puzzle's theme
Number of times this puzzle's theme word appears diagonally in the grid (to complete the puzzle, shade those words plus the Down answers that begin where they meet)
This puzzle's theme word
Just making things up, or a synonym for a three-word phrase describing this puzzle's theme entries
Possible theme, but not a description of this puzzle
Glen Campbell hit, the last word of which is this puzzle's theme
Angle (and a three-word hint to this puzzle's theme)
Pithy sayings (four well-known ones containing the circled word are the keys to unlocking this puzzle's theme)
Word that has two diametrically opposed meanings (like this puzzle's eight theme entries)
This puzzle's key theme word
Theme word inside this puzzle's theme words
Oxford American Dictionary's 2012 word of the year, and the key to this puzzle's theme
Economic term named the 2011 Word of the Year by the Oxford English Dictionary...and a description of 6 squares in this puzzle
Word hidden in this puzzle's theme entries
It can follow the last word of this puzzle's theme entries
Word before the first word in this puzzle's theme answers
This puzzle's obvious theme word
This puzzle's fairly obvious theme word
"Fun, Fun, Fun" singers (and this puzzle's theme)
"See ya!" (and a hint to this puzzle's theme)
Feature of this puzzle, and where the theme clues ought to have ended up
Something to do on Arbor Day (and a hint to this puzzle's theme)
Making a blunder (and this puzzle's theme)
Proper sort ... or a cry upon solving each of this puzzle's theme answers?
Bills and this puzzle's theme