Mortal or Venial Sin?

According to the Catholic faith, there are two kinds of sin, one of which blots out the goodness in your soul, destroys it, and denies you a place in heaven. This is classed as mortal sin and has to have three elements to qualify. It has to be of grievous nature, you have to be aware of its nature, and finally, you decide to go ahead with it, without any persuasion. If any of these elements are missing, it is classed as a venial sin, for which you can make amends by confessing your sin to the priest. You can then return to the straight and narrow path of righteousness. However, I believe genuine honest people use their conscience as a guide when faced with conflicts in their lives. In choosing right or wrong does not require any doctrine forced down our throats by a body of people who have illustrated many times that some of their members have proved to be evil.

Dare I say that there could be a humorous element in the attached article, about doing naughty things in a confessional box? I only suggest this because nobody in a sober mind would have entertained doing what this drunken couple did. They obviously did not know what they were doing, as they acquired forgiveness.
http://www.nowpublic.com/strange/sex-confession-box