A friend of mine once had Mormons come to her door. She had a somewhat disagreeable conversation with them, and they eventually left.

A while after that, there was a break-in near her house, and a couple of detectives came by to see if she had seen anything. Just two clean-cut white guys in nondescript suits. I guess they knew she was home, because when she saw them, assumed they were the Mormons, and just decided to hide in her house instead of answering, they became more and more aggressive with their knocking, and they were so persistent that eventually she gave up and answered the door to tell them off. By that point they'd become significantly heated at her hiding from them, so when she finally answered, they identified themselves and then instantly demanded to know why she hadn't answered the door.

She looked at them all angry in their suits, and managed to produce the statement, "I thought you were Mormons," before she collapsed in 100% helpless laughter. They had a somewhat heated conversation, with her laughing her ass off the entire time while legitimately trying to stop, and once she confirmed that she hadn't seen anything, they left, not really happy about it but with no other option.

Still laughing, she went back inside.