Boys of a certain age (read, almost any age), have certain favorite subjects. Body parts and bodily functions. Son #2 is 7; his filter is not well-developed. Son #1 has a more developed filter, but has found what he thinks is a way around the system: Science. See, apparently, in his 12-year old mind, if you are discussing body parts or bodily functions in the context of something scientific then it's ok. He's recently been attending a marine biology class during the summer, which gives him additional scientific fodder.
Now put the two of them together. At the dinner table. In a public place.
Son #1: Did you know that the (insert some random name) clam has an extremely long anus?
Mrs. Chako: Son, is this an appropriate conversation for the dinner table?
Son #2: An extremely long penis?!?!?!?
Son #1: I said 'anus' not 'penis' . . .
Mrs. Chako: #1! I said not at dinner!
Son #1: But he thought I said 'penis' not 'anus'.
Son #2: Yeah, I thought he said penis (laughs at the simple mix up).
Mrs. Chako: Boys!
Son #2: But he said 'anus'.
Son #1: Do you even know what an anus is, #2?
Mrs Chako: Guys!
Son #1: Its where your poop comes out.
Son #2: (Chuckles and shakes his head) Oh. (Looks at me) I though he said penis.