A term coined by Greg Lford, it is the definition of the feeling of being so extremely high that your like a tree that has been chopped down and just laying there. Comes from other definitions of "Chopped" which is a feeling of being very very high.
By taking one hand in the shape of a karate chop and slicing it down on your other hand's palm is the visual representation of being chopped, making it easier for those around you to understand how your feeling.
Jordan: The Lion King is such a awesome movie
Mitch: Yeah dude, that was a fat ass blunt we smoked
Jerrica: Hell yeah nigga, how you feelin greg?
Greg: *makes a chopped hand motion* im fuckin chopped like... fuckin chopped.