What are the rules of writing a 对联 (chinese couplet)?
平仄 can not be understood by a Chinese who only speaks Mandarin or some dialects, as I mentioned in my answer to the previous question "Different kinds of writing in Chinese". In mandarin, in many cases, 平 refers to the 1st and 2nd tone. 
The pattern of 对联 derives from the classic poems, a word-match is enough.
Nowadays, we usually write a 对联 at a celebrating time, e.g. the spring festival, or on the day when you get married, etc., and paste it besides the gate of your house to celebrate the event. As it is written to celebrate something, the content usually refers to good things like "be fortunate, be lucky, be happy, be healthy, etc.", so I think your example would not be considered as a 对联. Of course, you can use it in a humorous way, but I think you won't paste it.