It is a fact that the human mouth evolved to suck cock.
Besides being used for eating and speaking, our mouths are also an elegantly designed sex organ that evolved specifically to give a cock pleasure. Our lips are designed to stimulate the cock from the head down to the base. Our mouth cavity is populated with numerous dexterous muscles and soft vagina like cheeks. Our tongues have a texture designed to stimulate the head of the man's cock and the pleasure nodules under it. All of these adaptations were designed to give your man an orgasm as his cock moves in and out of your mouth. Your lips are designed to capture your man's sperm for swallowing. This was not an accident. We are born with the instinct to use our mouths to give a man a uniquely pleasurable orgasm no vagina can replicate.
It is natures way of helping men bond with each other.