It's likely you're referring to the Hawaiian greeting "Shaka", which is a gesture made with the pinky and thumb extended while the other fingers are curled into the palm.
The word "Shaka" itself isn't Arabic, and it's not commonly used in Arabic-speaking cultures. If you're looking for a similar gesture in Arabic culture, there are many ways to greet someone, but none are directly analogous to the "Shaka."
It's possible you've encountered a word that sounds similar to "Shaka" in Arabic, but without more context, it's hard to provide a specific answer.
Can you give me more information about where you heard "Shaka" or what context it was used in? This would help me understand what you're looking for and provide a better answer.