I think words that describe something gross should have a 'kh' somewhere. There's wasikh (dirty), and kherbana (busted, wrecked when describing object, or rotten, when describing something edible). People draw out the 'kh' sound to show their disgust.
My friend's son, at a year old, would stand in his crib and say 'ikkkhhhhh,' especially if he knew he was doing something he knew he shouldn't be. It was one of the first distinctly Arabic sounds he learned, I think because he heard it so much. Whenever someone caught him rooting through the garbage or the diaper pail, they'd say 'ikkhhh,' and pull him away. Laughing when he said it back didn't help keep him out of the dirty diapers.
I've heard badly behaved people described as having 'rancid blood.' As one of my flatmates put it:
نقوله (دمه زنخ) عن بني أدم عندما حركاته مش منيح