According to Slash Film on Sept. 3, on the set of "Star Trek Into Darkness", Simon Pegg decided to play a prank on his fellow actors. He made up an elaborate lie stating that it would be necessary for them to wear this "neutron cream" to protect them from the neutron damage in the laser room.
Currently, the video of this prank on all the actors had made it's way to YouTube so anyone watching can also get a laugh.
J.J. Abrams gives a commentary on how they went about doing it and how since it was the last day of shooting that it would be humorous way to end filming. The clip more than likely had been documented on the upcoming Blue-ray release on Sept. 10 and now fans can see the reactions of Benedict Cumberbatch, Zoe Saldana, Karl Urban, John Cho, and Chris Pine.
One would indeed get a laugh at their reactions when they all realize that the whole thing was a prank and how they were transitioned into finding out about it mostly by reading lines to a scene via cue cards or through reciting a liability waiver.