The story
Borrowed from Hokkien. See Hokkien 結結 /结结 (kiat-kiat, “to combine; to fuse; to bear (fruit)”), 桔/橘 (kiat) as in 桔仔/橘仔 (kiat-á, “tangerine; mandarin orange”), 傑傑 /杰杰 (kia̍t-kia̍t, “outstanding; remarkable; clever”), 結果 /结果 (kiat-kó, “to bear fruit”), etc.
Etymology from Wiktionary, CC BY-SA 4.0.