I thought the same thing. This is not a prank by some stupid kid. The type of dopey American deliquent who would be tempted to do a prank like that would not know fine details like the fact that some people cross their sevens. The fact that "jihad" was spelled inconsistently makes me think this person is not a native speaker of English.
I will go out on a limb and guess that since the person left out the vowel in the last syllable of jihad, writing "hd" instead of "had," it may be that the person is not a native speaker of any European language. I think it would be an odd mistake for a native speaker of almost any European language to write a syllable that does not have a vowel in it. I admit that I am probably reading too much in it.
The question marks and the 9s lean towards arabic or farsi script and the way the small a is scripted is very unusual in the US.