I’d think that Darth Vader would have a hard time with coffee. I mean he wears a helmet all the time, not exactly a headgear that works well for drinking things. Perhaps that is what he was doing inside that ball thingy, chilling and having a cup of joe.
If Vader did drink coffee, he would have it black. But he could damn well Force-stir his own mug of Joe if he wanted. The result would look just like the coffee and milk vortex inside this self-stirring Darth Vader mug .
To stir with this mug, you don’t need to be strong with the Force, you just need to press the thumb button. It will automatically spin your coffee into stirred up goodness. I think this might be perfect for hot chocolate too, which always seems to have powder left in the bottom. The mug sells for $14.99(USD) over at ThinkGeek.