I figure that "tacoing" is a typo but I can't work out what it should be.
What is a taco, or tacoing a wheel?
Originally from this question
To taco a wheel means you've bent it so badly its a write-off and cannot be salvaged through truing.
This is significantly worse than going out of true, because the rim will be creased or torn, spoke holes will be pulled through on the outside of the taco curve. A damaged rim alone is not a taco, there has to be a folded wheel to earn the title.
Tacoing normally happens on the front wheel, and the usual cause is side-loads caused by having the wheel not facing the direction of your travel. That is, an aggressive turn, or a poorly landed jump can all push the rim over, exceeding the wheel's lateral strength maximum limits.
A Taco in progress: Thankfully this chap already has his full-face helmet on; going to need it in about 1/20 of a second. Video http://www.pinkbike.com/video/91552 More info http://imgur.com/qR5RnYt .
Why is it called a Taco? because the wheel looks vaguely like the Mexican/American taco
Potato Chip - tend to be less damaging than a taco, and can be stomped back to shape.
Buckled / Buckling - this may or may not be damaged beyond recovery. I've heard it used for both tacoed wheels and also wheels that are slightly out of true.
others? Feel free to edit them in here.
The rider is pretty likely to have suffered physical injury too - Collarbones are are particularly vulnerable because the rider has gone Over The Bars (OTB) as the bike stops.
The wheel is very probably scrap. The best fix is to replace the whole wheel (rim/spokes/hub/QR/axle/rotor)
You should be able to salvage the tyre/tube, but examine closely the bead near the fold. Stretching may stop it from seating safely on the new rim.
Also check the forks closely. Look for damage to the legs, and misalignment. If you have problems getting the wheel out/in because the dropouts are too close OR too far apart then the fork needs servicing, or full replacement.
Headsets can suffer as well due to the leverage applied, putting steering bearings under additional load. Any doubts and you should disassemble the headset, and examine the steerer for bending, bearings for damage, and cups for dents.
Frames - a classic pattern of damage on older steel bikes was a ring of rust around the top tube and the down tube, approximately 50mm/2 inches aft of the headset weld or 25mm/1 inch after the end of a lug. However modern alloy bikes tend to be much better at resisting damage here. Do inspect for cracks, and include a periodic crack check in your usual maintenance procedure.
At best, you will be able to reuse the hub and rotor, and relate them onto a replacement rim and spokes. Examine them very closely for damage before reuse. Reusing spokes/nipples is a bad idea because the ones on the outside of the taco have been stressed and could be elongated. So the minimum damage is a new rim and spokes.