1) Someone with two butcheeks where there face should be. So instead of having a face, they just have another arse. Can be a result of being an asshat. Note: No-one can tell the difference between a cheekface's cough/burp and its fart.
2)Someone who's face is full of mischeif and cheek.
1) Person 1:Did he just burp or fart?
Person 2: I dunno, he's a cheekface.
2) You can see the mischeif in that boy's grin. He's such a cheekface.