system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did vanilla become synonymous with "plain"?
gpt
*Very* recently. The use of "vanilla" to mean "unexciting" or "the usual thing" only dates back to the 1970s, where it started to be used to describe people of normal sexual orientations and interests, in contrast to people who subscribed to unconventional sexual norms. Over the years the sexual aspect of the slang term got lost, so now we call anything ordinary or conventional "vanilla" without so much as a giggle.