What does pip squeak mean in slang?

In slang, pip squeak or pipsqueak means a small, insignificant, weak, or annoying person who is seen as unimportant and who tries to act more important than they are. It is a mildly derogatory term used to belittle someone, often a child, short person, or someone who is being bossy despite little power. For example, saying shut it, pipsqueak or who does that little pipsqueak think he is expresses contempt. The word combines pip meaning small seed or dot and squeak meaning small high-pitched sound, evoking a tiny mouse-like creature. It is not a swear word, profanity, or highly offensive slur, but it is insulting and can be hurtful, especially to children. It is considered playground-level insult, similar to runt, shrimp, squirt, or small fry. In some contexts it can be used affectionately or teasingly among friends, but generally it is demeaning. Historically, it was used in early 20th century military slang for small artillery shells, but modern use is purely as put-down for small person. So pip squeak in slang means little insignificant annoying person, not a compliment, but not extremely vulgar.