Dragon Cannon originated in 17th-19th Century China. During the Ming and Qing periods of Chinese history larger cannons had barrels cast in the shapes of Dragons or sometimes Tigers.
From Poly's:
"The Mystic War Cannon Mug is glazed in Fire Red with yellow and metallic accents.
Designed and hand-made by Poly.
Cast in porcelain and approximately 7 inches tall by 4 inches in diameter.
Holds approximately 20oz/600ml.
Maximum number of mugs for each casting is 100 and each is numbered."
*Also produced in Rusted Iron, Midnight Blue, Matcha, Jade Green, Black/Purple/Green, and Obsidian Black editions.