Guaranteed way to freak out the parents with minimum effort #1: Wander into the kitchen and casually say: "Hey Mum, how do you know if you're pregnant?"

(Story explained: writing a storyline for this fantastic roleplay involving my character becoming pregnant (well, what did she expect, she'd been shagging the guy silly for a couple of months) and me now knowing anything about this, I needed the advice of someone who did. When I finally scraped my mother off the ceiling and explained the situation to her, she was extremely helpful and the storyline is still going strong. It's a damn good storyline, and a fantastic roleplay.)