Green’s Dictionary of Slang

a general excl. of affirmation: definitely! certainly! absolutely!

1876		Scribner’s Mthly 13 162/2: I could make a speech that would tell, — yes, siree bob, tell like thunder!
1882		Sketches from ‘Texas Siftings’ 206: His friend informed him that he should have said: ‘Yes siree bob’.
1899		E. Robins Open Question 407: ‘Not the filly that won—’ ‘Yes, siree bob; won a pile fur Joicey’s father’.
1907		Appleton’s Mag. 10 554/2: "Yes, siree Bob, [...] He’s the durndest, queerest, crankiest greaser I ever seen.
1909		L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:v 362: rebob(tail), interj. ‘No (yes), sir, rebobtail!’ Probably originally ‘No, siree, Bob!’.
1913		H. Carter Boy Scouts in Rockies 188: Yes, siree bob, that was a picnic to an old Signal Corps man like me.
1921		P. & T. Casey Gay-cat 12: He gets setdowns. Yes siree bob: every time. Setdowns in the kitchen.
1925		Dos Passos Manhattan Transfer 67: ‘Is that way New York?’ [...] ‘Yessiree-bobby, behind yonder bank of fog lies Manhattan.’.
1931		(con. 1900) L. Riggs Green Grow the Lilacs I v: Yer time has come! Yes, siree, bob!
1943		J. Mitchell McSorley’s Wonderful Saloon (2001) 80: Yes, siree-bob, friend, I do have a message for you.
1956		M. Harris Bang the Drum Slowly 233: And the boys all said ‘Yes siree bob’ and ‘You said it, boss’ and ‘Sure enough’ and all.
1965		H. Wouk Don’t Stop the Carnival 281: Yes siree Bob, I’m going to miss this place.
1970		T. Southern Blue Movie (1974) 54: ‘Oh, it’s happened all right,’ he said, nodding, ‘yessiree bob!’.
1978		R. Price Ladies’ Man (1985) 168: Yessireebob. Just like some big fucking gerbil.
1986		D.Z. Phillips Belief, Change and Forms of Life 72: Yes siree bob, life is just a bowl of cherries.
1992		T. McGonigle Going to Patchogue 139: Yes siree, Bob, as the saying goes: you are gonna like this.
2007		J. Terral Seals: Combat Alley 205: Big stuff going down, yes-siree-bob!