Crazy Combos are activated by rapidly pressing the correct attack button during certain combos. If performed, a set of white circles flash around Dante, and then he performs high speed attacks with his weapon instead of the normal finisher for the starting combo. Crazy Combos are so named because Dante in Devil May Cry 3 will sometimes shout "Crazy!" after executing a Crazy Combo.
Million Stab - Dante creates a sword whirlwind with countless stabs, puncturing everything in the way and finishing with a deep blade thrust.
Crazy Dance - Dante sticks Rebellion into the ground, hops on its blade and spins around it in a similar manner to his pole dance move in the nightclub. He delivers kicks as he spins, finishing the attack by pulling out the sword and slashing everything in a broad arc.
Satellite, Million Carats and Reflector are the only Crazy Combos which do not require repeated presses to prolong the attack.
Some Crazy Combos, such as Million Stab, Crazy Dance, Million Slash, Hyper Fist and Wild Stomp have a special property: they keep the enemy alive with a "magic pixel" of health until their final attack. This means when executing, for example, the Million Stab on enemy and the attack is canceled, the demon will survive and the Million Stab could potentially be repeated. This trait is not restricted to Crazy Combos (Dance Macabre also works this way), but it a common feature of them.
Rapid Shot of Ebony & Ivory and Shotgun actually isn't a Crazy Combo, but the way to use it is similar (pressing the button repeatably).
Kalina Ann is the only weapon which doesn't have a Crazy Combo in Devil May Cry 3.