If you really want to step way back and look at things from a sociological level, a lot of things we humans do are odd. From hairstyles, facial hair, styles of dress, decorating ourselves with shiny metal and rocks, growing long fingernails and painting them bright colors, or painting faces to accentuate beauty. It's all weird if you really think about it, but just part of the human experience.
Isn't all to do with attracting a mate? A peacock has flamboyant feathers (yeah I know that's the male). Humans have make up, nice clothes, grooming etc.
Most of the oddities of human behaviour around mate choice make more sense in the light of what's called "sexual selection", a subform of natural selection. Peacock feathers are a great example of this, actually:
When you think of natural selection, most people are familiar with the concept that behaviours/traits that enhance the chance of survival are selected for, because they give you more time to stick around and breed, ultimately passing on your genes to the next generation.
Sexual selection however is where certain behaviours/traits make you more appealing to the opposite sex, even if that comes at the expense of your own survival. The peacock tail is a great example; they take energy to grow and carry around, and they make it harder to hide from predictors. Therefore a large peacock tail is a testament to how strong and capable, and how desirable of a mate, the peacock is.
Humans are no exception to sexual selection. High testosterone, for example, will give a male a stereotypical masculine appearance which, by and large, is seen as attractive. However, testosterone also suppresses the immune system. So if you look very masculine, and you haven't died of disease so far, this is a signal to a female that your immune system must be very strong - a trait that she would want to pass on to her children.
Human behaviours surrounding attractiveness are motivated in this same way. At the end of the day, you're always in some way trying to tell your potential mate how great your genes are, or how well you could protect/provide for your offspring.