It is a play on the phrase "Honest to god" that refers to the fact that blogs have been reputed as fact checkers in recent years.
I just avoided a crash on my way to work, honest to blog that was the closest I've ever come to death.
Example 2 -
Person 1: "I just got my second face lift in three years."
Person 2: "Honest to blog?"
Person 1: "Yea."
For further examples of such out of touch and stupid phrases, see Diablo Cody's shitty post-Juno writing credits (Jennifer's Body, Burlesque et.al.)
"Honest to Blog?"
"...dude, shut the FUCK up."