Packets have emotions.

What a well thought out proposal. Adding emotions to TCP packets, which are becoming increasingly important in our interconnected global world, could truly revolution the internet as we know it. The Emotional Web is the clear successor to the Semantic Web and the Social Web. It has tremendous possibilities for innovation and new startups. Note this statement by the author:

   This document does not seek to build a sentient network stack.
   However, this framework could be used to express the emotions of a
   sentient stack.  If that were to happen, a new technical job class of
   network psychologists could be created.

The idea of a sentient, emotional network stack being created may seem frightening to some people, but as the author notes:

   Some organizations are prohibited from using [the evil] mood by mission statement.

which should help alleviate some of the fears people may have of evil sentient networks.

Plus, by adding emotions to packets, we're a step closer to finally solving one of the most persistent problems in online text-based communication: determining if a message is meant seriously or sarcastically/facetiously.

Every now and then the possibilities of a new technology truly amazes me. This is one of those times.

I firmly believe that the Emotional Web is the future of the web as we know it.

I find the length field redundant. Two character emotions could be null padded, making three the standard length. This would save a byte for angry and evil. If evil and angry were removed (merged with sneaky and frustrated), emotions could be two bytes. Better yet, a lookup table could be used with a single byte. One other idea, which applies to all cases where 7bit ASCII is packed into 8bit bytes, is to have the eigth bit aroused on the last character

Aside from being a great RFC, it serves to note that 1 April RFC submissions to the IETF are due by 18 March!

Is it a joke, or is there any description to validate such a proposal?

Emotional sensitivity to computing machinery ought to be generally recognized, and not only on April Fools Day.