Illustrator - Draw a rectangle with one side zig zag line

Hi guys. Am trying to draw a cream coloured rectangle with one side having a zig zag line. Something similar to the zig zag line on this website here . Any ideas the best way to go about doing this???

Have tried using the filter distort>zigzag for one side of the rectangle, but when I try and add a colour to the rectangle is does not place the color round the zig zag area properly.

Any advice / tips would be great.

Thanks