KAMASUTRA says that.. sex is..

Duty- if done with ur wife..
Art- if done with ur love..
Education- if done with a virgin..
Tution- if done with ur teacher..
Job- if done with your boss/secretary..
Science- if done with a fertile lady..
Business- if done with a prostitute..
Social work – if done with ur neighbour
Charity- if done with a widow
Sacrifice- if done with ur own hand