The word "please" is easy to misuse, especially if we put it in the wrong place or add too much stress.
For example, "Could I have a glass of water, please?"
As compared to,
"Please, could I have a glass of water?
In the first example the main part of the request (can I have a glass of water) can be expressed with normal intonation and if the "please" is stressed it is at the end, it doesn't change the intonation of the whole sentence.
However, if "please" is placed at the beginning of the sentence and stressed it can indicate frustration, importance or anger as it tends to influence the tone of the request.
Keep it in mind next time you ask for something, please. Please, be careful!