I prank my family every October and the best prank I ever pulled on them was 6 years ago. At that time I worked on campus at UCCS and I had their Public Safety call my dad. They said, "Are you Mr. _____?" x "Is your daughter Laura _____?" x "Well sir, I am sorry to be calling you. Your daughter Laura was involved in an accident on campus and we are sorry to report that she was fatally wounded." After a pause, I came on the phone to announce the prank. It's downright mean but it's the best prank to do.
My suggestion for Jackass would be to take this prank and make it even more believable. For example, to have a friend dress up like a police officer and go to the home of one of the Jackass members. Personally, I think it would be best played for Ape, Bam's mom. I think she would have the best reaction. Anyway, have them ring the doorbell and announce their son's death. After a brief moment, the member who was assumed dead can show up. To step it up even higher, I would have that parent taken to a "morgue" to identify the body. And when they go to take a look, the person would come to life. That would be a killer prank to pull!