This!
Never shall the two mix.
A boss I had once told me, "Everything counts. Don't think because we're out having dinner, a beer, or are seeing a ball game together means you can let your guard down and drop the work facade."
He threw a christmas party at his house for all the staff one year. One guy got crazy drunk but was not obnoxious, just entertaining. Boss didn't approve. He was the first guy fired when we had cutbacks 1 year later.