Getting Paid
The term expresses an exceptionally good performance by someone

The term is used in such a way that if the person (who the term is being directed to) actually is getting paid for whatever s/he is doing, then merely saying the term (and technically expressing the obvious) actually means to express that that person is going above and beyond the job requirements and should be getting paid a lot (maybe more than s/he is getting paid).

If money is not already involved then it just expresses that the person is doing such a good job that it's like s/he is getting paid and still going above and beyond the requirements.
Example 1:

(Childris works as a cashier in a grocery store making an hourly wage of 7.50$)

Childris:  Hey, did you see me yesterday?  I scanned through 227 items and had all of them bagged within 5 minutes

Fellow Cashier:  Hell yeah I did, you were getting paid!

Example 2:

Person 1:  I've been training to play basketball all summer, so I challeneged my younger brother 1 on 1 and he beat me 15 to 2

Person 2:  Wow, your brother is gettin' paid!