Ok this achievement is very easy and can be done straight away from the beginning, once you are near a vehicle you can jump onto its roof.
So first of all walk into the road near the cars and once you see a lower roofed vehicle press
this will activate Chase McCains police whistle and hold up his police badge which will stop all surrounding traffic.
Please see Chases Police whistle stopping traffic image below:
Now stand next to your chosen vehicle and jump onto it’s roof, if you land onto its bonnet/hood you cannot jump again so walk off and jump up again!
As soon as you are onto the roof you will automatically start to balance onto one leg this is where your 30 seconds starts, you do not need to touch or move your character during this time either.
Please see images of Car Surfing below:
As soon as your 30 seconds are up that magic sound, POP achievement unlocked.
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