Colloids are a type of mixture. Unlike solutions, in which one substance is completely dissolved in another. In a colloid, very fine particles of one substance are suspended in another, so small that they don't separate easily or terribly fast. Compare with suspensions, which can separate fairly quickly (i.e. oil and vinegar salad dressing)

For a an idea of what the poll answers actually mean:
Gas-in-Gas: Gremlinn is correct, this isn't a colloid.
Gas-in-Liquid: Foams (Whipped cream)
Gas-in-Solid: Solid Foams (Sytrofoam)
Liquid-in-Gas: Liquid Aerosols (Bug Spray)
Liquid-in-Liquid: Emulsions (Mayonaisse)
Liquid-in Solid: Gels (Butter, Cheese)
Solid-in-Gas: Solid Aerosols (Smoke)
Solid-in-Liquid: Sols (Milk, Paint, Blood)
Solid-in-Solid: Solid Sols (Glass)

I think Solid-in-Liquid is the best answer, since one of those items keeps you alive.

- Auto "All info stolen from Wikipedia" Mator