No, not talking about a swimming pool here. One has to wonder, when and how many astronauts/cosmonauts nipped a little bourbon, vodka, sake, beer, wine, etc. between space walks, exercise, and running science experiments?
It's rumored back in the Soviet days, that vodka was part of the USSR's standard allotment of provisions for MIRs inhabitants. It was also rumored that a cigarette or two were allowed, although that remains largely unconfirmed.
There's also been a history of astronauts using their very limited personal allotment of space/weight to take things meaningful to them. Alan Shepard brought a golf club head and ball, Buzz Aldrin brought consecrated bread and wine and celebrated the first Eucharist on a heavenly body in our Solar System other than Earth. It remains to be seen if other civilizations in other systems and galaxies have done the same, but pretty sure for our Solar System that is true. So there is concrete (okay, anecdotal since they wouldn't broadcast it) evidence that wine (in sacramental form) has traveled all the way to the moon.
I'd have to think a number of astronauts have brought a little something something to celebrate their trip of a lifetime. Think how many times you went somewhere and the trip was made all the more meaningful by breaking out a beverage of choice to commemorate?
There is probably a non-trivial stash of alcoholic provisions on board. Having been permanently occupied since October 2000, there have been many a birthday celebration, space milestone (see video below), even new fatherhood worthy of a cultural tip of the glass.
In fact, The Ukraine appears to have featured a vodka drinking "experiment" on a local TV news show. I don't speak Ukrainian, but the tags at the host site imply that indeed this is how to drink vodka in space (skip to the 2 minute mark unless you know Ukrainian and can follow the dialogue). The crewmember is Yuri Malenchenko.
There are PR reasons against a government space agency making this public. In the era of people being hypersensitive to government's every dollar spent, and NASA (in particular, as compared to ESA, FSA, JAXA) in need of nothing but positive publicity, it doesn't make sense. I even recall that briefly on Twitter/Twitpic, a St. Arnold floating bottle cap on ISS was posted, it seemed to be taken down within minutes as I sent the link out to friends and many were too late and I've never found it again (presumably didn't pass muster for the public affairs office of NASA)
I submit this censorship of sorts is the wrong approach. As the space shuttle winds down, NASA and its international partners are missing out on a golden opportunity. The beer and liquor industry are heavy hitters in the advertising world. How much would they chip in to "sponsor" a happy hour event on the station? These days, when upwards of 6 residents permanently float around in the ISS, with over a dozen there during Shuttle Missions, the idea that European, Russian, American, and Japanese astronauts could sit down, each holding up a beverage of their home nation (beer, wine, sake, vodka, etc.), and toasting to human space exploration (with ad banners in the background) would be worth way more than a 30 second spot on the Super Bowl. Well, that is debatable, but the agencies could use this money in a way that would be socially acceptable, too. Funding scholarships for science and engineering, funding outreach programs in schools, facilitating trips and tours of facilities to those who couldn't otherwise afford it.
I certainly would not pass up an opportunity to have a swig of something in space and I'm sure other astronauts haven't passed it up either. One has to wonder to what extent or whether or not it will ever become more mainstream, as ISS will be utilized for upwards of another decade.