This is definitely a prefect example of how a small joke can escalate into a great prank.
Simon Pegg managed to fool the cast of Star Trek Into Darkness, including Benedict Cumberbatch, into believing that they had to wear a special “Neutron Cream” on set to prevent them from the small amounts of radiation that was floating about.
The joke continued to grow to legs and soon the whole production team was involved in the prank.
In an interview with the Graham Norton Show, Cumberbatch (Khan) explained how he was fooled by Pegg (Scotty):
“We were in a really futuristic laboratory with lasers that were trying to split a target smaller than a human hair to create a continual form of energy,” he said. “And I was like, ‘Wow, this is the real deal, what can’t we touch? What’s safe?'”
“I was gullible and did what I was told. It’s America and there is a lot of health and safety!”
“I should have known,” said Cumberbatch. “They had me, completely had me. It was really very funny.”

Below, Pegg explains the prank further to Jimmy Kimmel:
What a legend!