Green’s Dictionary of Slang

pappy adj.

(US) old, esp. exhibiting the signs of the old.

[US]D. Maurer Big Con 212: I never saw an old pappy con man.
[US]C. Himes Blind Man with a Pistol (1971) 169: What’s come over these young people, Digger, while we been chasing pappy thugs?

In compounds

pappy guy (n.) (also papy guy, poppa guy) [guy n.2 (1)]

(US tramp / und.) an old man.

Eldridge & Watts Our Rival, the Rascal 195: The aged victims -who are usually selected as marks for the ‘gold brick’ trick and its dependent schemes of robbery - are technically known as ‘Pappy Guys’ in the lingo of bunco.
[US]H. Green Actors’ Boarding House (1906) 69: Say, he’s a nice, kind, old pappy guy. [Ibid.] 138: He trimmed the beards of the old ‘poppa guys,’ as he disrespectfully termed the various soiled old men.
[US]K. McGaffey Sorrows of a Show Girl Ch. i: Some old pappy guy out in Chi was making a noisy fuss that the chorus ladies stay up too late nights.
[US]C.B. Chrysler White Slavery 113: And what makes these pest holes possible? A lot of old licentious papy guys.
[US]D. Runyon ‘A Nice Price’ in Runyon on Broadway (1954) 194: There is an old pappy guy with a chin whisker.
[US](con. 1920s) J. Thompson South of Heaven (1994) 47: An old pappy guy, which is what they call any old man on a pipeline.