Heres a rather odd one;
If you jump while standing still on a pile of Hollow bricks with a Baseplate on top + Jump, you will be slightly inside the Baseplate, untill you move. You can also crouch, and get stuck Crouching, also stick your head through the Baseplate. You can also Crouch to walk around inside it (Slightly).
I see no way you can use this to your advantage, but who knows?
Edit: This seems to work sometimes, but not always. Someone else test to confirm this please?
DoubleEdit:
Also another Bug to save posts;
When i join a game that has Weapon_HaloRL, Weapon_CC_RPG+Mk2, or Weapon_Thor, i disconnect with a reason "Cannot find shape: Weapon_(Thor/CC_RPG_Mk2/HaloRL)/ExplosionSphere.dts". Is that the Game, or the Add-ons screwing my up?
(Also, downloading them doesnt fix..)
Triple Edit: Just found out, turning off Download Explosion Shapes fixes :D