1. [1910s+] (UK/US/Aus.) a short term in prison [the UK/US versions are somewhat longer, about twelve months, than the Aus., which is three months].
2. [1940s] (US black campus) constr. with the, a college lecture.
SE in slang uses
[late 19C+] (US) sleep.
[mid-19C–1900s] a hat on which the nap has worn off.
[1940s] (Aus.) a sneak-thief.