Green’s Dictionary of Slang

(US) a euph. abbr. of asshole n.; thus in the pig’s a.h., in very great trouble.

1932		(con. 1917–19) Dos Passos Nineteen Nineteen in USA (1966) 371: Well, you’re in the pig’s a.h. for fair, Joe Williams.
1967		N. Mailer Why Are We in Vietnam? 37–8: A high-grade asshole [...] is characterized by a specific and even unique property [...] a high grade of A.H. is not easily recognized as any kind of A.H.