How do you do a coffin in Skate 3 on PS3?

To perform a coffin in Skate 3 on PS3, first, gain some speed and then press the R1 button to crouch while in the air. As you approach the peak of your jump, press the Square button to initiate the trick. To successfully land the coffin, tilt the left analog stick downwards while in the air. Timing and positioning are key, so practice to get the hang of it!