Thought I'd share this as it's hard to get people to explain how to do them.
I've been learning to dirt jump and one of the most popular ramps is a side by side pair of near vertical step up jumps onto a mulch covered landing ramp (one a bit bigger than the other).
Confident doing straight jumps and laying the bike down a bit but I couldn't visualize how to get the tail to swing out.
Asking the locals proved fruitless as they just shrugged and couldn't really explain what they were doing. However chatting away last night about another jump which required a sideways move in the air to get lined up for landing and watching a competent rider doing it gave me an idea:
I jumped up the right hand ramp as normal but in the air tried to steer the bike to land on the left hand ramps' line. My body twisted, the rear of the bike tried to overtake me and then I steered back straight for landing. That was it, a smooth, completely unforced tailwhip which I then repeated over and over again.
Thought I'd pass it on before I too started to shrug and say "dunno, I just do them".
EDIT: Of course by 'tailwhip' I mean 'whip'