A nice insult in Russian language for a stupid person. Usually used when referring to a family member or a close friend. While you are calling that person stupid, you still retain the fact of not insulting that person. Can also refer to a person who is been very slow. This is an insult that deliveries the insult, but the person who you are calling teapot can not really get mad at you because teapot is a "nice" sort of insult. However, you are still calling that person stupid or slow, just in a nice way.
Leave that light on, stop been such a teapot.
Oh my god, he is such a teapot.
2+2 is 4 not 5, you are a very teapot person.