I have a doubt regarding drinking milk in a transparent glass in front of others. Is it permissible?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Drinking milk in a transparent or a non transparent glass is allowed. But what is not allowed for a woman is to uncover herself in front of marriageable men.

However, if the drinking milk, as mentioned in your question, is considered in your area contrary to the sense of honor then it is better to avoid it to protect your dignity and honor.

Allaah Knows best.