how to make slippery surface?

[Koksu120]

how to make slippery surface as seen in HL2 canals?

[[B.n.B] AlcyToronto]

Usually slippering is set by the texture used, I.E. ice/snow textures are slippery because they have a different inertia.

[KinoFlo]

Alternatively, you could set up a trigger which sets the accelaration and deceleration to a lower value.