Cylinder walk.

What exactly is cylinder walk and what causes it?

this is a guess, but I know on the stroke of the engine, certain periods of its duration, the rod is pushing the piston against the cylinder wall as well as pushing up. and if you have a ton of boost in there, then more force is pushed against the side of the walls and they shift. maybe could happen at extreme rpms too, but wait for people to back my theory up before counting on me being correct.