People tweet about beer in the evenings, especially on Fridays, according to a not-very-surprising-but-still-fun little report in the journal Epidemiology: Using Twitter to Measure Behavior Patterns
The study used timeu.se, a free searchable database of millions of Tweets. The site grew out of an excellent bit of research you might remember from last year that examined how average mood varies over the course of the day and year.
People tweet about and presumably drink beer (and wine) most in the evenings, especially on Fridays and Saturdays. Smoking-related tweets however were mostly flat, although there did seem to be a small peak in the mornings.
So I ran a few searches of my own, and I noticed that different drinks peak at different times. "Beer" is most popular in the early evening, closely followed by "Wine", but "Vodka" doesn't max out until midnight.
Looks like people are not following the old "beer before liquor, never sicker" rule.
Also, while wine gets the most tweets during the week, beer and vodka really take off at the weekend.
Cunningham A. John (2012). Using Twitter to Measure Behavior Patterns Epidemiology DOI: 10.1097/EDE.0b013e3182625e5d