As far as God's joke, more like protection.  Besides being more willing under the influence, your judgement is also more clouded leaving you to be more likely to do something that might be risky and be detrimental to your health...i.e. pick up a street-walker and request BBFS.

Physiologically, however, the answer is a bit different.  It has to do with alcohol's effect on the central nervous system.  It lowers inhibition (therefore making you more willing while at the same time impairing your judgement).  The effects on the flesh have to do with decreased sensation (ever felt your face go numb when you've tied one on?  imagine what that does to the little fella!).  Alcohol also decreases blood pressure,heart rate, and respsiratory rate.  For those who don't understand how an erection works, without sufficient blood flow and blood pressure an erection cannot occur.

This concludes your health lesson for today.

So you did get to the front of the line at the folk fest!