turn up one's nose

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To make the gesture of raising one's nose, as a sign of scorn, contempt or disgust.
• verb idiomatic, with "at" To regard with contempt or scorn, especially in conjunction with the gesture of raising one's nose; to treat with contempt or scorn; to ignore or disregard in a contemptuous or scornful way.
• verb idiomatic, with "at" To refuse, especially with disgust, contempt or scorn, and especially in conjunction with the gesture of raising one's nose; to refuse with apparent disregard about offending the offerer.