Payyan: gundu malli rendu rubai, un koonthal eri uthirum poo kodi rubai
Pen: panchu mittai anju rubai, nee paathi thindru thantetal latche rubai
Translation (mine, bear with me)
Guy: Jasmine flowers, market price Rs. 2; if they are from your locks, Rs. 10,000,000.
Girl: Some kind of candy, Rs. 5; you eat half and give me, Rs. 100,000
A brief calculation shows that the boy derives joy magnified 5,000,000 times when the item in question has passed via the girl, whereas the girl's joy is only multiplied 40,000 times in the reverse scenario.
All further derivations and conclusions are left as exercises for the interested reader.