Green’s Dictionary of Slang

1. (Polari) to fix, to tidy; to smarten up.

1970		P. Burton Lang. of their own: Polari, West End Homosexual Slang (typescript) (O.E.D. Archive) ii: A zhooshy quean is a grand quean, to zhoosh up is to get ready.
c.1977		(ref. to 1960s) in Gay News (London) 2-15 June 23/1: We would zhoosh [‘fix’] our riahs [‘hair’], powder our eeks [‘faces’], climb into our bona [‘nice’] new drag [‘clothes’], don our batts [‘shoes’] and troll off [‘cruise’] to some bona bijou [‘nice, small’] bar.
2003		K. Cage Gayle 105/2: zoosh adj. and v. • adj. smart, nice, attractive, (cf. bona, delicious, fabulous) • v. smarten up.
2019		P. Baker Fabulosa 293/2: joshed up looking your best.
2019		P. Baker Fabulosa 299/1: zhoosh, jhoosh [...] 4. to style (hair) 5. to primp or apply make-up.
2023		R. Milward Man-Eating Typewriter 19: Joshed-up to the nobbas in his gold-embroidered tux.
2023		Twitter 8 Apr. 🌐 [of graphic design] Font/kerning is meh though. Probably would have still preferred them to zhuzh up the old one.
2023		R. Milward Man-Eating Typewriter 80: [T]he dolly palones joshed-up festive with sparklies.
2023		S. Hart Once Upon a Prime 140: Apparently the graphic design department said it [i.e. an equation] didn’t look exciting enough visually—could I zhuzh it up a bit?

2. see juice v. (1a)