One of the big reasons social media is so powerful is the potential for what you create to go viral.  An example of this power is when these artists had a bad experience on United Airlines, wrote a funny song about it and now has been viewed 7,403,573 times on YouTube, in 6 months. 

On a much smaller, but potentially more relevant scale - think about your Tweets.  Often Twitter is used to broadcast information.  Ideally all of your followers see this message, and ReTweet (RT) it to their followers, and then their followers RT it and so on - creating a viral marketing effect.

On Twitter, you are allowed 140 characters to broadcast your point.  Let's say I wanted to be RTed.  My Twitter handle is @sbonert (8 characters) and the RT in the retweet is 2 charectors, plus a space.  So for someone to simply hit the RT button and rebraodcast my message as is - I need to allow for 11 characters, or my message can be a maximum of 129 characters (140 - 11- 2 -1 = 129).  If it is any longer than that, it demands that the RTer edit my main message which requires work, and could be a barrier to being RTed.  Furthermore, if you wanted it to be RTed a second time, you need to consider room for the third Twitter handle as well. 

Here is example of what something getting RTed twice would look like, so you can see these extra characters in action:

RT @mikesimonsen: RT @rachnicole: @sbonert I always had a hard time w/some of the boundary lines. Wicker Park vs. Bucktown?

You can see how the extra handles and RT charecters can add up and eat into your alloted 140. 

Moral of the story: If you are hoping something gets ReTweeted - Try to keep the Tweet under 120 characters.  Make it easy for people to spread your love.