Playing golf with clients is one way to 'mix business with pleasure'. [=to do something enjoyable that is related to your work]
I accidentally 'mixed up' the two files. [=I put each of the files in the place where the other one should have gone]
He 'got mixed up in' a plan to destroy the government. [=he became involved in a plan to destroy the government]
(..) Oh, hey, uh... We, uh... We brought you some stuff... so you don't get bored in here. So... Uh, I made you a new mix tape. There's some stuff on there I think you really might like. Guys. Guys, he's up. Will is up. Guys, Will's up. Guys, come on. (..)2016 TvShow: Stranger Things Title: Chapter Eight: The Upside Down Season: 1 Episode 8