Assuming someone comes to a beer mile more from the drinking side of things than the running side, how fast would their mile fitness need to be for a sub-6 clocking? A friend of mine came to me for advice on this subject, and I told him he needed to be at the VERY least in sub 5 shape, and that he would have a much better shot if he could run 4:45 or so.
For most runners, I think this would still be too slow for a beer mile under 6 minutes (I know I have never approached that time, even when I did a beer mile in 4:15 mile shape - just couldn't drink with any speed past halfway). However, if he can actually get the beers down in 15 seconds each - and keep them down - I figure he may have a shot.
He has run recreationally in the past, and is still active overall - I would bet his current mile shape is somewhere around 5:30. With consistent running and light workouts I am betting he could get down to 5 minutes in a couple months.