Is it sin for men or women to wear a thong? Why or why not? Is it sin for people to feel sexy by the type of clothing they wear. Why do women need to wear a bra? Why should men not wear a bra? Is it sin to have implants and or enhance your body?
What you wear underneath your clothing that no one else sees is a matter of your own comfort. The claim is that thongs don't show through clothing, but wearing clothing that is that tight or thin that this makes a problem would be wrong for a Christian because it would not be modest. Some wear thongs to be seen in them, thus they are trying to maximize the amount of skin being shown while claiming to be covered. The pursuit of sensuality is not the direction Christians are to head. It is a focus on the world and its temporary pleasures. "So this I say, and affirm together with the Lord, that you walk no longer just as the Gentiles also walk, in the futility of their mind, being darkened in their understanding, excluded from the life of God because of the ignorance that is in them, because of the hardness of their heart; and they, having become callous, have given themselves over to sensuality for the practice of every kind of impurity with greediness" (Ephesians 4:17-19).
Women wear bras because their breasts need support, especially when active. Since men's breasts do not stick out, there is no need of support.
Cosmetic surgery is most often use to correct damage from injuries or diseases. For example, burns or cancer. As a way of restoring the look or function of the body, there is nothing wrong with the practice.
Some people use it to remove the marks of aging or just to look different from the way they were born. For the most part this later group is motivated by vanity or pride. This is contrary to the way Christians ought to behave. Again, it is being focused on this world, which is only temporary. "For we brought nothing into this world, and it is certain we can carry nothing out. And having food and clothing, with these we shall be content" (I Timothy 6:7-8).
Is wearing thongs in general not modest. Or not modest if seen wearing one?
Nakedness is the exposure of the sexual organs (a man's penis and scrotum or a woman's breasts and vulva). Any clothing that allows a view of these parts is considered equivalent to being naked. In Job 22:6, the Bible talks about stripping the naked of their clothing. In other words, it is possible to be naked and clothed at the same time. The phrasing implies a person who is thinly clad (wearing clothing whose material is transparent or thread-bare), leaving people with no doubts about what exists underneath the clothing. Another way a person can be naked is by wearing clothing that does not completely cover in all situations. God told the Israelites not to place the altar up where the priest would have to climb steps to reach it (Exodus 20:26). As the priest walked up the steps, there would be the possibility of the worshiper at the base of the steps seeing underneath the priest's garments. As an additional precaution, the priest's garments included short trousers that went from the waist to the thighs to cover their nakedness (Exodus 28:42-43). For a woman, the exposure of her breasts or her groin region would be considered nakedness (Ezekiel 16:7).
The exposure of the buttocks is also considered naked. "So shall the king of Assyria lead away the Egyptians as prisoners and the Ethiopians as captives, young and old, naked and barefoot, with their buttocks uncovered, to the shame of Egypt" (Isaiah 20:4). Thongs leave the buttocks exposed and so the person is still naked even while wearing a thong. A thong covers the genitals, but it does nothing to mask them, rather a thong calls attention to that area of the body.