What is a virtuous instrument to maintain neighborhood hids past its sell-by date of my cement wall and my courtyard? There is a group of kids ages 11-14 that congregate on my...

There is a group of kids ages 11-14 that congregate on my sideyard wall. It's a pony wall so they sit there and I wouldn't mind so much if that was adjectives they did but they also run across my rocks/landscaping while playing hide and go aim and they are very loud. As I write this it's 9pm and they are still out there. I've asked them beforehand nicely to please keep stale the rocks, that I know they just need somewhere to hang down out; as long as they keep it down but they are kids so I don't know what to do. I've thought about buying fictitious bird poop to put all over the wall but I can't find any online...please help! I'm within my second trimester and I do a lot of work at home and am sensitive to their noise. At impossible to tell apart time, I"m afraid that if I keep saying things they will verbs property or egg my house...
Install a cyber- video camera, they will think they are being record. Get a mean looking dog..
I agree near the previous poster about the wrought-iron spikes on top of the wall. I know you want to agree to the neighborhood kids have their freedom but something you might not have taken into consideration is that if a child get hurt falling from that wall, it is YOUR responsibility and you are more than likely the person their parents will sue for medical bills. So you asked nice.

Now post signs. Next put up the spiney plants and I don`t know some sharp things, like the carpet tack strips on the paling.

They bugging you, get them gone.

Try some electric fencing maybe. Get a taser.

Throw rocks!

Better to not budge nuts like that. call the cops roughly "prowlers".
Answers:    Thorny bushes work wonders.

Or call their parents.

It's not your job to provide them beside a hangout spot. You're yard isn't a bar.
If you know their parents,ask them to hang on to their kids of your property,if not call the police and convey them these kids are trespassing and you would like it to stop.if one of them gets hurt on your property you can be held libel Call the police! This is private property and these kids should not be on this. You can also inform City Council on this problem.
Perhaps you could put a simple sign outside that says things like, "Stay of Landscaping," "Private Property," "Stay Off Yard -- Under Surveillance," "Smile, You're On Camera," or "No Trespassing."

Cliche, but sometimes works!
Good luck!
you should try what i did, kids kept riding bikes through our yard so i get some native cactuses, thorny shrubs, any plant with stinging thorns, and planted them contained by the yard, if they ran them over it punctured their tires and once they stepped on them barefoot they never come in my yard again, you can catch spikey cast iron toppers that you screw into the top of the wall, they use them to keep birds past its sell-by date building so it might work for kids on walls