NBA 2K18

I found the easiest way to get this achievement is to head into my career and the neighbourhood. When loaded in walk about halfway down the street and there will be a street court on the left, just go over and join the line (chances are nobody is there anyway so you get straight on) once you are on just dunk the ball a few times and wait for the clock to run down.

The achievement should pop at the end of the time limit.

Walk out of the team's practice facility and head down the street. To the left, you'll see a court. Step on the blue circle and you'll be launched within a few seconds into a dunk contest. You don't need anyone else in order to get this achievement, and you don't even have to master the awful dunk controls... just stand there and let time expire and the achievement will pop.