Green’s Dictionary of Slang

1. (US) a switch-blade knife.

1941		F. Swados House of Fury (1959) 137: Naw, I bet Orchid pulled a switch ... Where’d she get that?
1953		F. Paley Rumble on the Docks (1955) 88: There was a click and a knifeblade sprang from Tony’s hand [...] ‘He’s got a switch!’.
1959		H. Ellison ‘No Game for Children’ in Gentleman Junkie (1961) 79: He felt like slipping his switch out of his high boot-top and sliding it to Monkey.

2. (Aus.) a telephone switchboard.

1949		L. Glassop Lucky Palmer 212: Joyce Butler’s on the switch.
1992		M. Frayn Now You Know 258: Why can’t he go on the switch?