"Do you have any markers around here?" you ask her, "Like, the thick ones?"
"Oh yeah, there should be some in the kitchen drawer by the fridge," she said, gesturing in that direction, "Help yourself."
"Thanks," you say, standing up and making your way over there, "Want anything while I'm in there?"
"A soda from the fridge would be great," Amanda replied, eyes glued to the TV once more.
You make your way to the kitchen and take a look at the fridge. Apparently, Amanda and her husband have one of those small magnetic whiteboards that they stick on the fridge to make shopping lists, hence why the markers are in here. Figuring you might save yourself the hassle of looking through unfamiliar drawers, you take the black marker already attached to the whiteboard and, after checking to make sure it worked, slipped it in your pocket. You then opened the fridge and grabbed two cans of soda from inside before making your way back to the living room.
"Thanks," Amanda said, catching the soda you tossed her. With one of your hands now free, you sit down and pull out the marker.
Figuring now's as good a time as any, you place your suggestion, ~You will not notice me writing on things with this marker, and anything I do write with this marker you will not consciously see. However, your subconscious will, and thus your mind will consider what is written as an accurate label for whatever the words are written on, no matter how illogical it may seem. For example, if I write 'table' on a chair, you will believe the chair should be used as a table and act accordingly, or believe something belongs to me if I mark it as mine. You will not notice anything odd about the way you are acting towards the objects in question.~
Amanda's eyes go blank, then readjust a moment after you stop speaking. You wait a couple of seconds for the suggestion to sink in, then think about what you want to write on first.