Green’s Dictionary of Slang

assfuck n.

[ass n. (2) + fuck n. (1)]
(orig. US)

1. [1940s+] an act of anal intercourse.

2. [1970s] an instance of cruel victimization.

3. [1990s+] an all-purpose derog. term of address.

In phrases

Assfuck, Nowhere (n.)

[2010s] (US) any place condered beyond civilization.