It's common in free software circles to try to disambiguate which sense of the English word free we mean by saying "think free as in speech not free beer".
Though one can still presumably get free beer from friends (or friends of friends) at parties and such, the example doesn't work very well in some situations. Without belaboring the point I'll just note that not everyone looks on alcohol use in a neutral way and so as an inclusive example, it suffers.
My college years were spent during or shortly after a time when alcohol-containing beverages began flowing somewhat less freely on campuses as policies began to tighten up. The drinking age was raised in a lot of places around that time from 18 or 19 to 21 as the federal government threatened federal highway funding for any state that maintained a lower age. Similar considerations tightened up laws around alcohol related promotions like happy hours and all-you-can-drink specials.
I suspect given Stallman's age that his free beer comparison was informed by experiences with the earlier regime, in which free beer was more likely to be used to lure students to social events at universities. (The joke about a bar band naming itself Free Beer comes from the same idea.)
In light of this change in how alcohol is viewed and treated (at least, officially) I think the free as in beer comparison is a little stale.
There is one consumable that seems to be in wide use to lure students to events on campuses, though. So, during a LibrePlanet lightning talk and to my HFOSS students I've proposed using this for the gratis side of the comparison:
Free as in pizza.
(Pizza in its most widely recognized form also challenges people who have certain dietary restrictions, but pizza is famously mutable: Vegetarian, vegan, and gluten free pizzas honor the essential mutability of pizza as a class of foodstuffs in a way that alcohol-free beer does not really do for beer.)