That first "penetration" scene was done very easily--we see the EDGE of the block Lansing is holding with his left hand; Lansing mimes the rest--very believably. The carefully-chosen camera angle wouldn't work as well as it does without Lansing being able to suddenly stop his hand moving. The shot that still amazes me is when he reaches into the mail box. At first, it looks as though clever lighting hides the fact that there simply is no front on the box, just darkness. But then his hand and/or the letter he's holding pass through the paper notice on the box. No detectable matte lines.