Green’s Dictionary of Slang

worries, nervousness; also attrib.

1974		G.V. Higgins Cogan’s Trade (1975) 156: It’s not this one and it’s not gonna be the next one, either, that’s giving me the yikes. [...] I don’t like having guys after me, you know?
1999		Indep. The Traveller 21 Aug. 5: And there lay the ‘yikes’ element: there would be just a flimsy membrane between us and the bears whose territory we would be invading.