Mr. Rewrite has a few problems with this headline, starting with it reminding him about Jim Carrey's disturbing behavior of late and continuing through its use of the underlined term.
First, and easiest, the correct spelling is graffiti -- two Fs, one T. Mr. Rewrite often sees botched references to grafitti and graffitti.
Second, Mr. Rewrite isn't about to accept graffiti as a verb. One sprays, etches, draws, etc., etc. graffiti on something. One doesn't graffiti something. The Webster's New World Dictionary lists graffiti only as a plural noun (the singular: graffito -- more on that later). It also lists graffitied as an adjective and graffitist as a noun for a person who puts graffiti on things. Even Dictionary.com, which allows pretty much anything, doesn't accept graffiti as a verb.
Graffiti is a bit of a danger zone when it comes to agreement. Pretty much every reference book -- and Mr. Rewrite, for that matter -- is ready to accept it as a singular mass noun (e.g. The graffiti Jim Carrey painted on his home makes me fear he's lost it.). But Garner's Modern American Usage notes that plenty of reputable outlets will give it a plural verb (e.g. Graffiti have started to appear on Mr. Rewrite's back wall. Maybe Jim Carrey has moved into the neighborhood.).
Mr. Rewrite's suggestion on this last point: Write around it so you don't have some language hawks running after you screaming, "Graffito IS. Graffiti ARE!!!"