Instead of taking stuff away from a grave (
grave robbing) you are adding
to the grave site.
Usually taking the form of revenge; by having lunch sat on their grave, tossing all the empty beer cans, wrappers, and crumbs over it. Then
lighting up a few smokes flicking the ash about and grinding the butt into the headstone.
To finish you can then urinate and/or take a dump on the grave, using the flowers or cards to wipe with.