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Here's how
Pour the corn syrup, glycerin, water, and vegetable oil into four separate cups.
Add a few drops of red food colouring to the corn syrup. Add drops of blue to the water. Do not colour the oil or glycerin.
Pour the red syrup into the glass or jar. Try not to let it dribble down the sides.
Use the funnel to pour the glycerin down the inside of the glass. Pour carefully to avoid disturbing the bottom layer.
Wash the funnel.

Repeat step 4, first adding the blue water, then the oil, washing the funnel between steps.
The liquids will stay in separate layers if you are careful not to shake the glass.

Why?
Each liquid has its own density. You added liquids in order from highest to lowest density.
The oil stays on top because it is least dense.