wisenheimer
\ WAHY-zuhn-hahy-mer \, noun;
1.a wiseacre or smart aleck.
Quotes:
She scoffed at Cindi Su's meekness and diffidence, but she also thought if you were a girl in these United States, being agreeable and dithering probably got you further than being a hulking wisenheimer who skipped grades in school and aspired to be a race car driver.
-- Karen Karbo, The Stuff of Life , 2003
There was a wisenheimer , Phelps Boykin, I reported to. He was still staring straight ahead, and as if by magic I imagined I was inside his head, feeling time snag and ravel up, the present overwhelmed by the past.
-- Lee K. Abbott, "The Talk Talked Between Worms," All Things, All at Once , 2011
Origin:
Wisenheimer is an Americanism that arose in the 1910s. It is a combination of wise with heimer as an extracted form from surnames with this ending.
Dictionary.com