Here's a series that can help you illustrate "plugging into" something. These plugs can help convey receiving energy, distributing energy, initiating an interaction, tapping into a resource, connections, and so much more. The cords on the downloads are not lines, but they can be replaced with a line that you draw to connect one object with another. Think about what this might do to org chart layouts: hierarchies of energy/information flows, etc.
Customizing the plugs
Group the plug sets first and then rescale (hold shift key down as you resize). If you want to adjust the size of the wires, you can replace what's in the download with lines from the Shapes menu. That way you'll be able to connect two objects, regardless of where they are on your slide.
Color variationsApply fill color only to the plug and receptacle. If you apply a border line, the prongs will get to wide and the receptacle will get too thin to work correctly. You can use any size line you wish if you add connector lines. A heavy, high-point-size line would probably be best so that the line and the plug/receptacle look balanced.
Don't use 3D. The two pieces of the plugs won't work together if you do use 3D.
Don't use shadows because there will be an issue with layering.
Gradients, patterns, and pictures
Nope, not these either.
Simple animations are okay. If you're using the plugs/receptacles with straight lines, you can animate with a motion to connect them. But if you're using plugs/receptacles with a cured line, the animation won't look realistic because the wire won't move like a wire would.