Yesterday we took our dd to a local theme park.
Parked car early morning....Car park is grassy and manicured with plants and grass.
The park is kept generally pristine with employees constantly picking litter....sweeping etc....
Had a great time returned to car....
Cars all parked in lines.... As we approached ours I saw the car next door throw about 3 things from the window.
A bulging soiled nappy
An empty wipe pack
Various wrappers
I said loudly 'think you've dropped something' they carried on reversing and just laughed.
As we packed up car ....the litter pickers came around and I pointed to the pile and said 'not ours....awful what people leave for you to find'
'Its about the tenth nappy in this car park today....we are used to that ....get far worse' 
I started a mini rant. Dp agreed was vile but not worth getting annoyed over.
AIBU to get visibly annoyed about this. Do any of you?