Green’s Dictionary of Slang

underpants, knickers.

1964		Gujarat Govt Gaz. Apr.-June 553: Chuddies and petticoats will be supplied only to those female security prisoners of either class who use 5.5 Meters sarees.
1991		R. Khare Return to Mandhata 42: I had nothing, just an old dress and torn chuddies.
2001		M. Jaleel People Unlike Us 170: [T]he policewallahs found him later without any clothes on. Not even his chuddies.
2007		G. Duncan Bloodstone Papers 178: Kate was flannel-washing Dalma and Lucy while Robbie, naked but for chuddies, hung by his hands from the corner of the water tank.
2017		S.M. Barton Frosted [ebook] ‘Kiss my chuddies, you soggy excuse of a dough boy!’ Felicity bellowed.