Introduction to Gac Fruit for Westerners Filed in Gac Fruit on Mar.10, 2009 There is a fruit that grows on vines in Southeastern Asia that looks like nothing else on Earth. This large fruit, about the size of a grapefruit, is related to the gourd and as it ripens it puts on a beautiful show of colors, starting from neon green and working it's way up to bright hot-pink. Unripe Gac Fruit Ripe Gac..