Green’s Dictionary of Slang

bamboo adj.

[a very common plant in the area]

1. [1900s] (US) Chinese.

2. [1920s–60s] used of a Westerner who has ‘gone native’ while stationed in the Far East; thus of the accented Eng. some use (see cite 1934).

3. [1950s–60s] eccentric, mad [f. sense 2].