You can't be serious. A vac leak is a unmetered into the combustion chamber leak of air......

Commonly these are found in places such as carb throttle plate shaft seals, intake manifold gaskets, in Stomberg carbs a split vac diaphram, any hoses entering the intake manifold operating a vacuum operated device like a vac pod on a dist, or heater controlls, and the vac master for the brakes. On injected cars even the seals at the injectors can leak.

These are vac leaks because the pistons travelling down ward taking on a fresh charge of air fuel mix can and will be leaned out if there is a vac leak. Mac