Will somebody please enlighten me...

I'm begging you. Please enlighten me as to how a "terrorist" looks. Because obviously i'm not getting it. How do you associate an article or clothing to a murderer?!
my father was sharing with us a story about his day. And he said I was at work and i saw somebody come in to the room dressed like a soldier holding a ghutra  and agal in his hands. What is a ghutra and agal you may ask. A ghutra is basically a red and white scarf wrapped around the head (part of arab/khaleeji culture). Like this man:

The red and white scarf is the ghutra and the agal is the black thing holding it down. Anyways back with the story. So the man comes into the room where my dad's working dressed as a soldier and holding a ghutra and agal in his hands. My dad goes over to talk to him and ask him what he's holding (my dad full well knows what it was he's holding but he goes over to see what the man would answer him). So when my dad asks, the soldier man says 'I'm dressed up as a terrorist". Full ignorance. my dad just turns his back on him and leaves.

When my dad was sharing this "experience" with us I got really mad. Full on mad. Because truthfully it wasn't fair. Like how shallow are you going to be anyways? Go to the point of taking a person's CULTURE and using it as a sign of terrorism?

Oh, you know what? maybe I'll go and wear a mini skirt and tank top in public and be like I'm dressed as a "prostitute". That's nice isn't it? Just because some people have no background and culture doesn't mean they have to look down on other people's culture.

People piss me off. I'm glad I wasn't there because I would have slapped that man hard across the face. My parents can stand that stuff. They probably have enough wisdom to ignore the ignorant. Obviously I'm not that mature. And obviously I'm outspoken.

So will somebody please enlighten me as to how a terrorist LOOKS?