The look on my neighbors face when I showed her my dogs vet records: priceless.
He got out last month while I was in New York, last time I leave him with my roommates when I go out of town for more than a couple days, and went over to the neighbors. Long story short - she comes over this evening yelling about him getting her dog pregnant, and how I was going to pay for him ruining her. I didn't even answer her, just closed the door and went and got his records. Specifically the page showing where I got him fixed last year because I didn't want to deal with a situation like this.
I wish I'd managed to get a picture of her face. It would make it easier to remember.