blow one’s top v.
1. [1920s+] to lose one’s sanity.
2. [1930s] (US black) to get drunk.
3. [1930s] (US tramp) to commit suicide, esp. by shooting.
4. [1930s+] (also blow gaff) to lose one’s temper, to become violent [gaff n.2 (4)].
5. [1930s+] to express intense emotion; to become very excited.
6. [1940s–50s] to talk too much.