Brainstorm
Brainstorms are divided into two types: internal and external. Both types are caused by Brain Clouds.
External brainstorms
An external brainstorm is when someone's brain is affecting the weather. Some people have Super Brains that are so smart that they can telekenetically affect weather patterns just by thinking! Unfortunately, none of these people are meteorologists, which explains why weather forecasts tend to be so innaccurate.
If you see a giant brain floating in the sky that is using lightning bolts to blast stuff, you are seeing an external brainstorm. Run away!
Internal brainstorms
Internal brainstorms occur when a miniature thunderstorm occurs in someone's brain. These are usually lethal since brains don't like getting water and electricity shot through them alot. They tend to die people.
Brianstorms
Brianstorms are internal brainstorms that occur inside Brian.
Conclusion
Thinking is a dangerous habit. Remember kids, don't think!