Virality cannot be planned for and, for the most part, none of these moments went viral. Most people in the world didn't knew about the mission. These kinds of moments aren't "allowed" to happen, they just happen because humans are humans. NASA, and scientists in general, are not at all a bunch of stiff book worms like the stereotypes dictate. People are people and will make jokes and try to keep work environments light. There's enough stress on trying to fulfill the mission and come back alive already.

They were also super busy though, this mission was a test flight and, well, they spentost of their wake time doing science and testing the spacecraft. Not much time for PR stunts and goofing off, really.