Go to a parts store several towns away and pick up several valve stem tools. Get five of your closest and most trusted buddies and find the lot where they park all the district school buses. Sneak in the night before the last day of school and remove the valve stems from all the school buses and place them in a plastic bag. Hide the bag somewhere on the property so they will find them but not right away. This will cause no actual damage because they can be screwed right back in. What it will do is cause every school in the district to have a very ****ed up morning. High school kids will be waiting for a bus that's not coming and it will trickle down to middle and grade schools. Sit back and laugh and keep your mouth shut until after you walk.