(v) to take someone else's (or a brands) Facebook username as your vanity URL thus 'squatting' on their username
(term only applicable if the username is nothing close to your own name/brand)
(n) a person who partakes in the act of facesquatting
Someone else took the vanity URL I wanted, so I decided to Facesquatt on my friend's name.
See Facebook.com/Obiefernandez (Mike Pence's Facebook page)