Or in the Layers palette, Alt-drag the appearance bump from one object onto another.
Or drag the little thumbnail of the appearance preview from the top line of the Appearance palette and drop it onto the object you want to style.
Or turn on the Appearance options of the Eyedropper tool, and then eyedropper the appearance from one object onto another.
Note, however, that all of these methods will transfer the entire appearance from one object to another. So if you had a single path with a yellow fill and green stroke, which then had a 3D effect (or any other effect) applied to it, and you used any of the appearance transfer methods, the destination object would also become filled yellow and stroked green.
So if you are going to want to transfer only the effect, the thing to do is put your original object in a group, and apply the effect to that group. Optionally define your graphic style at this point. Then put your destination object in a group as well, and apply the style or copy the appearance onto to that group.
The style will say that it has no stroke and no fill, and therefore will have no visible preview in the Graphic Styles palette. But since you are applying it to a group, it is fine that the group has no fill or stroke of its own; that won't interfere with all the objects inside the group keeping their own fills and strokes.