There are these times where you need to bribe and you do not know what kind of bribe to use: cash or sex? Luckily, José Rodrigues-Neto has just produces a handy and rigorous guide for your decision making.
Clearly, sex as a bribe is less efficient than money, for reasons related to the deadweight loss of Christmas. However, sex may be less detectable. Also, and the author does not take this into account, less expensive to provide for some. In short, the optimal bribe is money when there is a large efficiency loss with sex, but it is sex when the receiver likes that a lot. It could be both in between those extremes.
Of course, there are other favors than sex that could be offered. Meals and tickets to events, however, have well defined monetary values unless there is some rationing (think, Bayreuth tickets or meals with politicians). In that respect, a Wagner opera is like sex. There, I said it.