In short, there's a tacit suggestion on the part of the site that what one enters in that field should be more than a direct summary of what one is doing (or has done); there should be some sort of hook, some angle that makes it interesting even in the most rudimentary sense.
Let's look at a theoretical example:
"At the store buying oranges" may reflect the task one is undertaking but that, in and of itself, fails to warrant one pulling out one's mobile device and harnessing the vast wireless network (including orbiting satellites) in order to make all one's friends see that in their news feed.
"At the store buying oranges. When did they get so expensive?" is better, as there's an implicit commentary on the prices of produce.
However, better still would be something like "At the store buying oranges. When did they get so expensive? Oh, and I saw one that looked just like Glenn Beck's head" (along with an accompanying photo).
Better than that would be "At the store buying oranges. Heard Glenn Beck blame the Obama administration for driving up prices and start to cry when he thought about how real Americans couldn't afford citrus fruit. Didn't realize he dragged that blackboard with him everywhere he goes."
Of course, that would only be likely to be something one could post if one shopped at the same store as the popular radio and TV personality. Again, it's merely a hypothetical. (It's probably far likelier that Beck would lament the price of apples anyway.) But with any luck Facebook users would get the idea about what is worthy of subjecting to those who were
In short, it should be more interesting than this post. Thank goodness no one reads blogs any more...
(Not that this applies to any of my Facebook friends, of course.)