Two young Mormon missionaries are spreading the good word around South-East Asia when they accidentally walk in to a brothel

This becomes increasingly clearer to the two young men as the attractive, scantily clad women begin to make poorly veiled sexual entreaties in broken English. The two have practically no knowledge of, or experience with, women, and begin sweating profusely when the truth dawns. The first missionary is getting up to leave when his colleague stops him and points out shakily that this is an opportune moment to bring salvation to some fallen souls. After a reluctant agreement, the two hold eachother and say a silent prayer for strength.
The two purchase an hour of a lady’s time for, it must be said, a very reasonable price. However, once the smoky eyed, buxom woman brings them to her room, it becomes very clear she has little interest in the teachings of Joseph Smith and proceeds to deliver her own lesson on anatomy. The two men retreat before her seductions but their strength is failing. By the time the lady finally seems to understand their increasingly weak insistence on chastity vows, their faces are beet red, they are shaking violently and the crotches of their khaki pants are being put through a rigorous tensile strength test. When she suggests oral sex instead, the two youths look at eachother and see that their resolve has left them.
Afterwards, the two missionaries walk in silence through the Bangkok streets. Finally, the first wipes his mouth and stammers “I did not know women had such big penises”.