Erm, people should get over fucking poor taste...
But seriously, I don't understand the thought process behind it.
Someone dresses up as a middle eastern terrorist, a boy from the middle east is angry about it? Surely the costume isn't slandering the entire middle east... it's slandering terrorism in the middle east? So why is he upset, surely he should be doing the same? Is he in fact a terrorist? And unhappy that he is making fun of terrorists? If anything, he's insinuating that.
I dunno, I just think that if somebody dressed up as an IRA terrorist, nobody would give two shits, but because it's a terrorist in the middle east, then that's suddenly an instantly racist thing to do, because they are nothing but victims.
And besides, if it's not who you are, then why are you even angry about it? Because it has nothing to do with you in that case...
I always thought hat's how most costumes work... You take a popular cultural icon, and use it for comic effect... If you get offended by that, then sorry. But freaking deal with it... It's not totally destroying your identity as a person...