Macon Daily Telegraph (July 2, 1916), p. 15:

"Company D, of Columbus [Ga.], brought an innovation into camp yesterday with some of this 'rah, rah' college stuff. Their yell runs like this:

Rah, rah, rah, who are we?
We're the boys of Company D,
Rough and tough, hard to bluff,
Always fighting and never get enough."

Plain Dealer (Cleveland) (Feb. 14, 1977), p. 35:

"Loving Lines to Valentines ...

Tom

I'm rough and and I'm tough
And if that's not enough
I love you baby
And that's no stuff.

Bebe"

The version I heard (once) in the early '60s was "'Im rough and I'm tough and I know my stuff."