Does your teacher know anything about dancewear for males? You need to purchase a dancebelt (male thong athletic supporter) that is very snug fitting and more supportive than a jockstrap. It is designed so no lines show under your tights. Purchase dancebelts at dance/ballet stores or on the internet. There are also unitards, biketards and thongtards made for males. Wear either tights or the -tards over the dancebelt. The dancebelt allows you to wear tights as tight as needed. Also the dancebelt allows for a better fit for tights. Red tights are okay to wear but make sure you wear a skin tone (beige) dancebelt as a white or black belt might show through the tights. Ask your teacher if you can wear a unitard or biketard which also covers the top area which takes care of the "women's bathing suit" problem.
Brief underwear should not be worn under tights for two reasons. One, the lines of the underwear will show through the tights and, two, brief underwear does not give the support a male needs when wearing tights. A dancebelt is what almost all male ballet dancers wear as well as lots of guys who workout in tights. Also, the dancebelt is designed to reduce possible injury. There are two ways to wear a dancebelt with one way being the preferred and sometimes required. Not to be graphic but the preferred and usually required way is in the "up" position.
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