Things You'll Need
Plastic heat shrink tubing
Heat gun or shrink oven
A limited number of Christmas lights can usually be strung together end to end and plugged in male to female. However, there is the danger of a child getting hold of a string of lights and possibly sticking something into the female plug. It is recommended that you purchase at least one string of lights with no female end connector to avoid this problem. If you already have your lights and don't want to buy another set, it is possible to remove the connector plug at the end.
Make sure the light set that you want to remove the female plug from is disconnected from any wall sockets or other Christmas lights.
With a set of wire cutters, clip the female plug off, leaving as much extra wire as possible.
Wrap the ends of the wires separately with electrical tape, then wrap the tape over both wires, securing them together.
Cut a piece of heat shrink tubing that is big enough to fit over the wires but will shrink to the proper size after it's heated. Let the tubing extend over the end of the wire about 1/4 inch.
Use a heat gun or shrink oven to shrink the tubing as open flame will likely damage the tubing.
Rotate the wire and apply the heat evenly until the tubing conforms to the shape of the wire, then allow the tubing to cool.