According to the manual i got with my gallardo its called a "Burn-off" sart!
This is taken from my manual:
The "Burn-off"start function of the egear system is a drastic procedure. It aims to take advantage of all the capabilities of the vehicle when starting with the maximum acceleration possible.
In this way the highest performance, in terms of acceleration is obtained.
The burn off start function of the egear system is only enabled under the following conditions:
The vehicle is stationary
first gear is engaged
the ESP has been switched off by using th appropriate button on the dashboard
the egear is set to the sport mode
If just one of the above conditions is not present, the burn off start procedure is not enabled.
Under these conditions, by flooring the pedal as quickly as possible, the system enters into a special operating mode which increases the engine revolutions automatically, releasing the clutch at the best speed to take advantage of the maximum torque.
Hope this helps!
Havent tried it yet myself as the roads here in the uk are quite wet at the mo.
Cheers