A slang expression meaning to be incarcerated
, with reference to the fact that one does not do much of any importance in prison except wait and count the time until the apointed date of release
. Metaphorically, any unpleasant
situation which can only cured by waiting
for it to pass.
Also Doing <unit of time>, eg Doing six months for shiplifting, as in the old joke:
A: I say, I haven't seen you in five years, what have you been doing?
B: Five years.