How can I make my birthmark less noticeable?

Okay I have a coffee color birthmark on my knee it's oval shaped and is pretty much the size of my knee I hate it. My skin color is a light brown and it's very noticeable since it's two different color tones. It's summer now and I really want to wear skirts and shorts but without the constant stares on my knee and the same obnoxious question "what's that on your knee" someone please help me out what can I do to make it less noticeable I've tried makeup but I cant seem to find the right color or make a good color mixture that will go with both the lighter part of my leg and the coffee color on my knee HELP!!!