Originally obtained from wrestling and Tony Hawk video games, when a wrestler/skater does a series of standard moves correctly in a row, they go into "special" mode, where they pull off extraordinary, jedi-like moves.
In real life, going into "spesh mode" means that you are going above and beyond the call of duty, with little regard to your own saftey, welfare, and social stature, for a good laugh or a good time.
It also remains popular in the world of video games, where you can "uberspesh" and "blink yellow" while beating someone's ass.
Jonesy was speshin' so fucking hard on the dance floor last night. He did the Sprinker, riding the lawnmower, the Electric Slide, and even followed it with a pants-splitting "flying V."
Even though he was in spesh mode, he still didn't get any pussy.