I think this is a fancy way of saying that if people have a day off to party, they are a bit less likely to vote.
Cambridge Journals Online - British Journal of Political Science 44, 1 (January 2014)
Social Capital and Voter Turnout: Evidence from Saint's Day Fiestas in Mexico
Matthew D. Atkinson and Anthony Fowler
Social capital and community activity are thought to increase voter turnout, but reverse causation and omitted variables may bias the results of previous studies. This article exploits saint's day fiestas in Mexico as a natural experiment to test this causal relationship. Saint's day fiestas provide temporary but large shocks to the connectedness and trust within a community, and the timing of these fiestas is quasi-random. For both cross-municipality and within-municipality estimates, saint's day fiestas occurring near an election decrease turnout by 2.5 to 3.5 percentage points. So community activities that generate social capital can inhibit political participation. These findings may give pause to scholars and policy makers who assume that such community activity and social capital will improve the performance of democracy.
If I am sitting around drinking with my friends, I may find it harder to get up and stand in line to vote. Unless, as happens, a political party is providing the drinks and the transportation. It may not be more complicated than that.