A Losi Grind is when you grind the front truck and deck with the back truck on top of the edge.
Losi is like a feeble only backwards.
Invented by Alan Losi as a vert trick. Possibly as a stall on the coping. I don't know much about the history because it is from before I skated.
This trick can be done as a stall on coping. It is easier to 180 out. The pop in straight from a stall is tough. The back trucks can get caught.
If you want to do it on a ledge or rail use a back lip motion and land with the truck locked. Sick trick but not easy.