Step 1: Do It
Note: my holes are about 1/2 inch by 1/4 inch
Put one piece of tape lengthwise over the hole.
Put another piece of tape laterally over the hole (perpendicular to the first piece).
__DO NOT__ loop either piece over and around the edges of flipflop. This will cause problems in the future.
Flip the flipflops over and put a piece of duct tape lengthwise over the hole.