[–] FrozenFire74 1 points 2 points (+3|-1) ago 

Rubbing dry hands together helps to create friction, but the lack of liquid prevents the heat from being retained on the skin. A small amount of water helps with the abrasion (thus increasing the friction), and since water retains heat so easily, the right amount of liquid will help to trap the heat to the surface of the hand.

[–] cool_and_froody 1 points 1 points (+2|-1) ago 

because hands evolved to increase friction when wet by wrinkling up. to make them usable in the rain

[–] HorseIsDead 0 points 0 points (+0|-0) ago 

Cohesion and adhesion of water.

[–] Mustard_of_puppets 0 points 0 points (+0|-0) ago 

If you wash your hands with bar soap instead of that girly stuff that leaves you slimy you can make hella hot friction fast.