Party promises are those plans you make at the end of social gatherings1 where one, if not both, promiser never actually intends on following through.

Party promise（派對諾言或聚會上的約定）指的是在某個社交聚會結束時跟其他人做出的約定，但約定的一方，甚至雙方，其實并沒計劃真的履行這個約定。

For example:

-Dude, we should totally grab coffee sometime soon!

-Yea, totally!

－哥們兒，大家應該找時間一塊喝咖啡！

－嗯，必須要的！