Wiseacre
/ˈwaɪzeɪkər/
Definition 1 of 1
Pro Tip 1/3Colloquial Usage
Used in casual or informal conversation, not in formal writing or speeches. 
My uncle always plays the wiseacre at family gatherings.
Pro Tip 2/3Mild Disapproval
Suggests annoyance but is not extremely offensive. 
The teacher wasn't amused by the wiseacre interrupting the class.
Pro Tip 3/3Not Actual Wisdom
Implies a lack of real knowledge or wisdom; sarcastic in tone. 
He's always acting like a wiseacre, but he rarely knows the answer.