Start with two triangles of a fabric of your choosing. I went with the leopard print of the three.
Use hem tape to bond two of the three sides of both triangles together, right side to right side.
Afterwards, one side should be left open, like so ^
Turn it inside out
Trim the corners so that the ends sticking out are no longer there
Place the insides of your shirt's collar inside the collar tips. For a more finished look , use a safety pin to pin the back part of the tip to the collar, or you could do as I did and go for a more unfinished look, pining the collar tips in front.
purple bananas and fudgeballs