The interesting thing here is that the joke wasn't really: dongle as childish sexual innuendo. What they found funny is that they were sitting at pycon making

The interesting thing here is that the joke wasn't really: dongle as childish sexual innuendo. What they found funny is that they were sitting at pycon making an obviously childish joke. It's only funny because its so obviously stupid. It's a signifier between two friends that they are relaxed enough to make retarded jokes. So they weren't being childish, it's normal behavior for sophisticated people to occasionally deliberately make stupid jokes.