Pointy ones with good aeorodynamics make little splashback, big round ones that hurt on their way out are like a fat bastard belly flopping into a swimming pool. They're the ones that get me. I'm usually euphoric after passing such a beauty, like surviving a car crash. They usually arise after I've been at a festival on a four day diet of beer, meat, bread and psychadelics.
The pebbly ones aren't so bad, the splash they create are like an anal bog water kiss.