What does Boxing Day have to do with boxing?
1560s, "full of snot," from snot + -y (2). Meaning "impudent, curt, conceited" is from 1870. Related: Snottily; snottiness. Snotnose "upstart" is from 1941; snotty-nose "contemptible fellow" is from c.1600.
: He's just a snotnose kid
An importunate upstart; a neophyte, esp a knowing one: some snot-nose in New York (1941+)