You can pick them up, toss them around, make them fall indefinitely through two portals, drop a cube on them, etc. Also try the following. Use the incandescent particle field in front of the exit. The computer voice said before that all objects other than yourself and the portal gun will be destroyed. Pick up a turret and toss it into the energy field. The turret will say "ayayayay" as if being electrocuted and disintegrate.