smart alec

/S M AA1 R T AE0 L IH0 K/
noun
  1. 1

    One who is given to obnoxious or insolent humor.

  2. 2

    One who is pretentious about their own cleverness or knowledge.

  3. 3

    One who is obnoxiously self-assured; a show off.

  4. 4

    A well-dressed person.

Source: https://en.wiktionary.org/wiki/smart%20alec, https://en.wiktionary.org/wiki/smart%20aleck