We always electrify ours. ;)
They were placed on someone else’s property without permission.
that ups the ante. see someone put a sign in your yard, now you know what to do.
I like the idea of rubbing poison ivy all over the edges of the signs. Undetectable until 4-5 days later and impossible to prove it wasn’t natural (at least not around my place!). Wear disposable rubber gloves or the joke will be on you!
Garden out front. Bury a 6 foot diameter kiddie pool in the garden and mulch. Fill the pool with pig manure, horse manure, cow manure. Add water. Place your sign in the pool. Cover the pool in a layer of woodchop mulch level to the surrounding garden mulch. Sign vandals are knee deep in a moat of manure before they realize it.