The bullseye is the act of revealing ones behind (also known as mooning) and spreading the right and left buttox, or cheeks, to reveal the anus. This portrays the common bullseye target as it is colour-coated to match the red and brown and sometimes black pattern of the poopie-hole. This is also known as a Two Cheek Peek.
At first I thought Kleydis was mooning me, but then I noticed he was spreading his cheeks and giving me a bullseye. Boy, does he do a poor job of wiping!