gaining unfair advantage in form of deception
"That dude tried to short shift me"
"I short shifted jimmy by telling his client i was him"
"I caught her out lying so i short shifted her with her best friend"
When shifting in a manual transmission while in the midst of a race you under shift the gear of the car because your not watching the RPM gauge and not shifting at the prefered shift time.
Dude, you could tell that that newb didnt know when to shift cuz you could hear him short shifting the gears in the car