A paragraph which is largely nonsensical, due to its over-emotional or angry nature. They tend to be sweeping, poorly-structured bursts of emotion from teenagers and people who're stressed out, often aimed at no-one and everyone at the same time.
Angry person - "I'm so angry!"
Friendly person - "What's wrong?"
Angry person - "It's fine, I'll just post a few rantagraphs on my blog later."