Is there a word for a person who is solely interested in mindless social fun? A junior I know told me that EL&U is stressful because it's full of "serious"(lack of a better word here) people, of course as the site suggests, we need to post something which is more than just mindless social fun. I suppose I could use unambitious but then there are always people who are both ambitious while still enjoying mindless social fun. In fact, it would be great if you could suggest a cute and funny nickname to ridicule him but not something which is downright insidious.
Various terms exist for men and women, although you may not get a single word with exactly the value you want.
Party girl - defined at reference.com as "a girl or woman who is interested in little else besides attending parties" is fitting, though applies to women only. Party animal is the non-gender-specific version.
Social butterfly, one who flits from social gathering to social gathering, which has a slightly negative but humourous connotation.
Hedonist, sybarite, epicure - someone interested in the pleasures of the flesh, which would include mindless social fun but also pleasures done solo or in a duo.
Socialite - someone who likes attending swanky social occasions, with little or no overtone of condemnation (but more cocktail parties than keggers).