A Facebook group about general trivia stated that the soldiers in the famous "Biggus Dickus" in Life of Brian were unaware of the jokes in the scene, and therefore their attempts to refrain from laughing are actually genuine.
I've found an IMDb Trivia record about it:
When Michael Palin as Pontius Pilate addressed the soldiers daring them to laugh, he was truly daring them. The soldier extras were ordered to stand there and not laugh, but not told what Palin was going to do. Palin, in fact, can barely stifle his own laughter when saying "Biggus Dickus" in front of the soldier asked if he finds the name "risible".
But other than that, no credible source, like an interview with the actors or anything alike.
Is there any source that can verify this trivia item?