do (one's) duty(redirected from do its duty)
do (one's) duty
1. To do, undertake, or accomplish that which is expected or required from one. I know it isn't easy facing off against the lowlifes of this town, but you're on the police force and you have to do your duty.
2. To urinate or defecate, especially a house pet. I hate standing out here in the cold, waiting for the dog to do his duty.
See also: duty