electronics abbreviation of alternating current/direct current, by 1898. As slang for "bisexual," 1959, said to have been in use orally from c.1940; the notion is of working both ways.
Practicing both heterosexual and homosexual sex; bisexual
: I think she does it AC-DC
[fr the abbreviations for the two types of electrical current, alternating and direct; an appliance that can operate with either type is marked AC-DC]