Spaghetti straight is a term used to refer to someone (often but not always a woman) who considers themselves straight until they are "hot and wet." The term plays on metaphor. Spaghetti is straight until it gets wet. Once boiled (wet), it bends. So “straight” people are said to be “straight” only until a situation changes (usually sexual/physical context).
This term can be considered derogatory and even homophobic, as it leans in to the idea that people can "become" gay. However, it is also embraced by some people to refer to themselves, or even others in a playful way.
A similar term, "spaghetti girl," is used fairly often in the lesbian community to refer to straight women who don't know they have the potential to be into women until they've been with one.
Origins of the Term
The origins of this term are unclear, but Google Trends data suggests it began appearing as a search term around 2012/2013. The term may have emerged based on a popular meme from the 2012 movie "Pitch Perfect," in which two of the female characters have major chemistry and several "near miss" moments with homoerotic undertones. The movie even spawned a popular fan fiction, Bechloe, in which the two characters are explicitly romantic and sexual.
