like it's my job
to do something excessively, repeatedly, or to an extent that it becomes one's trademark
alyssa is such an alcoholic. she drinks likes it's her job.
like it was my job
Engaging in an activity repeatedly and/or skillfully enough that its as if you were getting paid to do so. Particularly applies to non-work-related activities.
I drink like it was my job. Not to mention on the job.
like it was my job
When in trouble for doing something that you didn't ave to do, the expression "like it was my job" can be used
"Why haven't you done the laundry"
"Pfft, like it was my job"
"Pfft, like it was my job"