Male surplus
A “male surplus” refers to a situation in which there are significantly more men than women present in a sexual or party-related setting. The term is used mainly in swinger and erotic contexts, for example at events where the gender ratio is heavily skewed toward men.
The phrase is descriptive, but it can also reduce people to a numerical ratio. In sensitive contexts, neutral and respectful wording is preferable. What matters most are consent, clear rules, and respectful behavior among everyone involved.