[joblessjunkie]

...And many apps don't make it 100% clear that wall spam is going to be the consequence of your choice, or that not sending spam is an option.

Send spam: "Click big happy green button to share!"

Don't spam: "Click tiny, scary 'X', which is followed by deliberately confusing confirmation, 'Are you sure you don't want to continue?".

They just keep asking you over and over; eventually you either mis-click or give in.