Coo-Coo is a bird enemy from Virtual Boy Wario Land, residing within the clocks found in Stage 10. Whenever Wario enters an area containing clocks, the long hand may rotate two to three times around the clock face before a Coo-Coo emerges from its door, resembling a cuckoo clock. The Coo-Coo then begins laying eggs which break upon hitting the ground, releasing Little Coos. These creatures chase Wario, quickly exploding like a bomb. Coo-Coos normally return back inside their doors after one to two rotations of the clock's long hand.
Coo-Coos may be sent flying off-screen if Wario bumps them. They are also defeatable by performing a Barge, or by using the flames of Sea Dragon or King Dragon Wario. Once a Coo-Coo is defeated, its clock door will remain open. The gate key of this stage is hidden within a Coo-Coo's clock, whose long hand rotates faster than normal.