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?