Definition - What does Forced Heterosexuality mean?
In the context of BDSM, forced heterosexuality refers to play (or a "scene") in which the submissive partner is forced, by the dominant partner, to participate in sexual activity with a member of the opposite gender.
Kinkly explains Forced Heterosexuality
It is important to understand, in light of the presence of the word "forced" in this term, that prior to any play a dominant and a submissive should negotiate what play they will be participating in. In these negotiations the submissive partner would consent to being "forced" to engage in forced heterosexuality.