Not enough fiber.
Not wearing enough hats.
In response to Drumersl
I'm sorry, but you don't get the joke.
In response to Smoko
Smoko wrote:

... too much fiber?

-- Data
In response to Android Data
No, just the right amount.
In response to Drumersl
Drumersl wrote:
Not wearing enough hats.

wtf? hats....that has nothing to do with this post!
In response to Garthor
Number 2... :D
In response to EGUY
I suppose not, I was refering to the number two problem with humanity from Monty Python's Meaning of Life
In response to Drumersl

"Among children, or when otherwise calling for subtlety, the phrase "number 2" can refer to the act of defecating (with urination being "number 1")."