Definition & Meaning of "anal invader"in English

What is the origin of the term "anal invader" and how is it used?

Anal invader is a slang term that developed in gay male communities by the mid-20th century to describe a man who performs the penetrating role during anal sex. The term uses a militaristic metaphor—"invader"—to emphasize the active or dominant role in the act, paired with "anal" to specify the sexual context. It is almost always crude and sexual, and outside of consensual sexual or erotic discussions it can be considered vulgar or offensive. Within LGBTQ+ spaces, it is primarily descriptive and emphasizes sexual roles rather than insulting character, but tone and audience still strongly affect how it is received.