Green’s Dictionary of Slang

papa n.

[SE papa, father]
(US)

1. [late 19C+] (also pap) an affectionate name used by a woman to her husband, lover or pimp.

2. [1920s+] oneself.

3. [1930s–40s] (US Und.) a Lincoln automobile.

4. [1940s+] a masculine lesbian.

5. [1950s+] an older homosexual man.

In phrases

hot papa (n.) (also red-hot papa) [hot adj. (1a)]

[20C+] (US Und.) a womanizer; a dandy .

real papa, the (n.) [cognate with daddy n. (6)]

[late 19C] the best, the ultimate.

In exclamations