A bug chaser is a person, typically an HIV-negative man, who intentionally seeks to become infected with HIV through unprotected sex. This behavior is part of a rare subculture where individuals eroticize the idea of acquiring HIV, sometimes as a way to attain a sense of community, sexual excitement, or other psychological reasons. Bug chasers deliberately pursue sexual encounters with HIV-positive partners with the goal of contracting the virus.

Bug chasing is often contrasted with "gift giving," where HIV-positive men seek to transmit the virus to HIV-negative partners. This phenomenon has been documented primarily among men who have unprotected sex with men (MSM) and is considered statistically rare, though it has received media attention and scholarly research since the early 2000s.

The practice has been controversial and subject to debate regarding its prevalence and underlying motivations, but it persists as a niche behavior despite the availability of HIV prevention measures such as PrEP and effective treatments.