Alcoholic drinks and Invisalign: Do I take my trays out for every drink and brush after every drink?

It's not a dumb question - probably one many people wonder and are too embarrassed to ask!
If you plan to drink with friends I would remove the trays until you are done. It isn't ideal to drink with trays in, and unrealistic to brush after each and every drink. Just replace them as soon as you're done drinking or when you get home. If you feel you had them out for a long time, I'd add an extra day or few hours to the current tray before moving on to the next. 

Alcohol should not damage aligner materials but red wines etc may stain your teeth.  Remember that anything you drink with aligners in will be trapped under the aligners and thus concentrate sugars and stains.  Depending on your frequency of "going out" and how long you are out may be something you have to determine.  Novadent "Soft" cleaner packets from Novadent.com are great at removing stains as well as getting some aligner wipes for quick cleans while you are "out".  Just do not stay out so late you forget to wear your aligners......