It's not often I get a story grooved right to me: Tomorrow is International Buy Your Priest a Beer Day.
I think this is a fabricated day, much like Truffles Day and Urinate While Sitting Day, but it's worthy of our attention, for all the reasons laid out in the linked article above.
I just wouldn't suggest doing it before Mass. (1) Do you like to drink before work? (2) It's arguably sacrilegious. (3) I witnessed a priest show up for Mass partly in the bag once; it wasn't pretty (the fact that it was Holy Thursday made it borderline scandalous, but in his defense, he pulled it together and celebrated Mass without a hitch).