Careful with the shape of her hand and fingers in the middle frame, this is something I also noticed in yesterdays sketch. I assume its supposed to be her left hand going in, but the finger lengths/angle and absence of an indication of a thumb made it look like her right hand was in his ass. Making the index finger longer or pinkie shorter would be an easy fix.One other suggestion - her fingertips hitting his prostate would make Sam go cross eyed in the bottom left panel ;)
Surprise buttsex? >.>Just had to say it. Love the look on his face.
I wish more artists payed as much attention to anatomy and the quality of their drawings as you.