Step 1: Cut a hole in a box
Step 2: Put your junk through that hole
Step 3: Have the person you're trying to rep open the box.
Dick in a box! (Also known as rep in these parts...)
(under the person's username you see three little boxes. Check the one with a check-mark and an x, and it will open a little box for you to approve [positive rep] or disapprove [negative rep])