Looking on the internet deeply has found these results:

on facebook is the most popular phrase on the web.

in facebook 187,900,000 results on the web	on facebook 12,060,000,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
They're sitting in their transparent cubicle In their open space, in facebook. Miss blair, I defrind Mr. Chuck in facebook and in life. In facebook, you're supposed to be who you are and there's, sort of, one model, which is that you're friends with people. or withhold their consent Miss blair, I defrind Mr. Chuck in facebook and in life. Thus even photographs of a highly personal nature appear in Facebook without them being able to consent Permission of KIPI Plugin application to upload photos directly. If not, user will need to manually approve uploaded photos in Facebook. to their publication.	So let's put pictures of you on facebook. [narrator] these are the default settings on facebook in 2005, You know who is my friend on facebook? You take one photo and post this on facebook, Friendly has gotten me 700 friends on facebook, one in each of the 50 states, 3 in guam. You just put it on facebook. I showed you his picture on facebook. Nobody's watching your kids' videos on facebook, I promise you.

in facebook

187,900,000 results on the web

on facebook

12,060,000,000 results on the web

More popular!

They're sitting in their transparent cubicle In their open space, in facebook.
Miss blair, I defrind Mr. Chuck in facebook and in life.
In facebook, you're supposed to be who you are and there's, sort of, one model, which is that you're friends with people.
or withhold their consent
Miss blair, I defrind Mr. Chuck in facebook and in life.
Thus even photographs of a highly personal nature appear in Facebook without them being able to consent
Permission of KIPI Plugin application to upload photos directly. If not, user will need to manually approve uploaded photos in Facebook.
to their publication.

So let's put pictures of you on facebook.
[narrator] these are the default settings on facebook in 2005,
You know who is my friend on facebook?
You take one photo and post this on facebook,
Friendly has gotten me 700 friends on facebook, one in each of the 50 states, 3 in guam.
You just put it on facebook.
I showed you his picture on facebook.
Nobody's watching your kids' videos on facebook, I promise you.