From third-plateau.org...
Yeah, that's what it's called, a separatory funnel. Here is a homemade version of one (but you could always find a glass one with a Teflon stopcock for about $10 if you have a scientific supply store in your area. You don't need the ring and ring stand, though. We used to use them "hand-held" a lot back in the ol' college days.
Here's an exerpt from third-plateau.org:
...bag with a slide-lock closure (e.g., ZiplocTM), big enough to hold the liquid. The plastic bags should be non-pleated. They will be used as separatory funnels.
(An approximate version of a separatory funnel can be) used to separate the layers. Pour the entire contents of the bottle into the sealable plastic bag, seal it, let the layers separate, clip off the bottom corner, and let the watery layer (on the bottom) drain out into the drain. Then let the organic (Dawn's note: fattier, less-dense) layer drain into the jar.