Green’s Dictionary of Slang

can opener n.

[SE can/can n.1 (4e)/SE can]

1. [1910s] (US) a sabre.

2. [1910s–40s] (US) a cook.

3. [1910s–60s] (UK/US Und.) any tool used for the breaking open of a safe, when explosives would lead to discovery; thus can-opener artist, a skilled safe-breaker.

4. [1910s–60s] (UK/US Und.) attrib. use of sense 3.

5. [1910s–60s] (UK/US Und., also can shooter) a safebreaker; thus can-opening, safebreaking.