Boner Sphere
The theoretical sphere which surrounds an attractive woman.
It is said that once a man steps inside that sphere, he will receive a firm and spontaneous boner.

Depending on how attractive a girl is, her B.S. radius may vary. The unit in which to measure a boner sphere is in veins popping. If the girl causes a boner with 3 veins popping, her boner sphere level is 3.