Take a solid sphere. Its surface (or "skin") is homeomorphic to the sphere. Now drill a hole through the solid sphere:
The surface (or "skin") of the resulting solid is homeomorphic to the torus.
This time, drill two holes in the solid sphere, like this:
Now the surface (or "skin") of the resulting solid is homeomorphic to the 2-fold torus.
Drill two holes in the solid sphere which "meet", like this:
To what is the surface (or "skin") of the resulting solid homeomorphic?