This is a simple classic that works for diverse styles, but especially for laid-back flows.
Drop your right arm to your side. Turn your palm up towards your face, and open it as if you were about to pitch a softball. Curl your pinky and ring fingers in to your palm, but keep your middle finger, index finger and thumb extended.
As you spit, wag it back and forth. Some rappers keep their arm low, close to their hip, while others bring it up and extend it away from their body. The idea is that as you’re flowing, you kind of look like you’re tossing off ninja stars like that old Sega arcade game Shinobi.