Two angry neighbors

Two neighbors had been fighting each other for nigh on four decades. Bob buys a Great Dane and teaches it to use the bathroom in Bill's yard. For one whole year Bill ignores the dog.

So Bob then buys a cow and teaches it to use the bathroom in Bill's yard. After about a year and a half of Bob's cow crapping in Bill's yard; being ignored all the while, a semi pulls up in front of Bill's house.

Bob runs over and demands to know what's in the 18-wheeler.

'My new pet elephant,' Bill replies solemly.