When someone is arrogant or stuck-up, you might describe them as snotty. You'll get in trouble if you answer your teacher's question in a snotty voice.
If you're new at school, you may imagine there will be snotty kids who won't let you sit with them at lunch—it'll be a pleasant surprise when they turn out to be friendly and welcoming. Snotty can also mean "clogged with mucus," like a crying toddler's snotty nose. This sniffly meaning was first recorded in the 1560s, while the "snobby" one came along almost three hundred years later.