Objects Edge Glitch
Object Edge Glitch - Glitch with can put props(cubes and etc.) across walls(Glass, Metal and etc. not fat walls). Possible only Single testchambers.
When an object is near the edge of a portal, it becomes capable of phasing through static props, glass, and perhaps other things we are not currently aware of. To perform this glitch, simply place an open portal near a window or door, pick up the object you want to phase through, and push it against the door/window. If this doesn't work, either the portal is too far away, it is closed (not connected with another portal) or you are trying to move the object through without touching it to the portal's hitbox. You can view the portal's hitbox by typing "ent_bbox prop_portal" in the console, with sv_cheats enabled.
This is only used in one testchamber in the entire game to date- Smooth Jazz. It is also possible in Portal 1.