Professor of Geometry: A kiss is the shortest distance between two straight lines.
Professor of Physics: A kiss is the contraction of mouth due to the expansion of the heart.
Professor of Chemistry: A kiss is the reaction of the interaction between two hearts.
Professor of Zoology: A kiss is the interchange of unisexual salivary bacteria.
Professor of Physiology: A kiss is the juxtaposition of two orbicular ors muscles in the state of contraction.
Professor of Dentistry: A kiss is infectious and antiseptic.
Professor of Economics: A kiss is that thing for which the demand is higher than the supply.
Professor of Statistics: A kiss is an event whose probability depends on the vital statistics of 36-24-36.
Professor of Philosophy: A kiss is the persecution for the child, ecstasy for the youth and homage for the old.