The female body is amazing but it can also be a bit annoying sometimes. For most of us, we can’t always get wet on demand. The vagina, when it’s in the right mood, creates it’s own natural lube when it is aroused. Lubricant helps accomodate vulva massage (external stimulation) and penetration. Without slippery slide-y lube, sex would be painful. There would be friction which would be followed by days of itching and agitation. Ouch!