Green’s Dictionary of Slang

(US campus) gigantic.

1972		oral testimony in Lighter HDAS I 892/2: Gigunda means gigantic and huge.
1997–2002		Hope College ‘Dict. of New Terms’ 🌐 gigungous adj. Huge, really big.
2002		‘Boul Mich’ on ABC 7 Chicago 6 Dec. 🌐 This BLT — with a ½ pound of bacon—and the strawberry shortcake, says it all about The Grill — American dishes in gigunda portions.