I don't know if this can warrant bad behaviour but King Charles III was nearly blighted for me by loud and annoying laughter. Sure it was funny, but this guy's laugh was over the top and loud enough to take me out of the moment. Worst thing was that his laugh was delayed, about two seconds behind everyone else so continued into the next lines. That and his laugh caused him to move around, and as he wasn't the smallest of men, moved my chair.
According to an article on Havers and Jarvis in today's Standard:
"Their characters John Worthing and Algernon Moncrieff are in their twenties, so the production is being presented as a show by a company doing a final dress rehearsal in the manor house of the woman playing Lady Bracknell. Simon Brett is writing an explanatory prologue before the play proper begins."