Examples that relate to mistaken signs for another person’s truthfulness include

Winking one’s eye with the aim to alert someone on an issue but the person in question thinks that you meant a different thing. For instance, a man who winks at a woman may be mistaken for wanting other relations with the woman like sexual relations. Yet another example of a mistaken sign would be waving. Some may interpret the same to mean “ come” while others would interpret bidding goodbye. In other instances where one would use the tick sign, some people may interpret that sign to mean getting a go ahead to do something while others may interpret the same to mean being sent away or being reprimanded in one way or another.
Question 2
An example of a euphemism that I have come across is a mother conversing with the daughter touching on sex in the presence of other peers. In this case, the mother uses expressions that explain to the daughter that her body is changing, and that sooner or later, she would start developing mountains on her chest. The mother also tells the daughter that visitors will visit her every month to mean that she would start experiencing her monthly periods. She later explains to her daughter that forests will grow on her body, to mean that the daughter will start developing pubic hair on her body. These kinds of expressions help in communication as Moore & Parker (2011) write. In this case, the euphemisms make it less embarrassing to discuss the body changes in the human body.

Reference

• Moore, B. N. & Parker, R. (2011). Critical Thinking. NY: McGraw-Hill Education.