How to Say the "something" in the phrase "Do something" I was trying to explain the meaning of the phrase "hang out" to a Chinese friend, and the first thing that came to mind was 一起做什么了, with me intending 什么了 to mean "something". He seemed to understand what I was trying to say, but I'm pretty sure I didn't speak correctly. 

This turn of phrase came to mind because I'm pretty sure I have heard someone say 什么什么了 as a placeholder to mean "whatever" or "something", signifying that the speaker doesn't care what the actual thing is.

Is this expression correct?
First you were right by using 什么 to mean "something" in Chinese. 

However, 了 is a past tense indicator, which was not supposed to be there because you didn't hang out yet. 

The correct way to say “Do something together” in Chinese is:

一起做些什么

or

一起做点什么