Take a little racism, throw in a dash of homophobia – definitely do not touch the Holocaust – and finish off with a sprinkle of incest. Voila: you have the perfect dark comedy.
TV sitcom audiences' appetite for edgy material has the programme-makers relentlessly pushing against the boundaries of taste and decency. So Derek, about a nursing home carer with an apparently undiagnosed condition, and Way to Go, about assisted suicide, are to be followed by even more frantic attempts to offend with dwarfist jokes when Life Is Short returns in coming weeks.
Writers defend their scripts by claiming they raise tricky subjects that otherwise would not be covered, but others say that they offend people who often cannot defend themselves.
Since the 1970s in Till Death Us Do Part – Johnny Speight's scripts got people laughing at, not with, the racist and xenophobic East End dock worker Alf Garnett – we have become ever more used to shock comedy.
But as we become more inured to what used to be unbroadcastable, sitcoms have had to mine ever deeper and darker seams. So where next for the sitcom – disabled sex, slavery, child abuse? Are there any areas that comedy still cannot tackle?
Yes, the Holocaust. Heil Honey, I'm Home! centred on the premise that Adolf Hitler could not get along with his Jewish neighbours. It was cancelled after just one show.
But Charlie Chaplin and others have managed to mock the Nazi leader without offending, so it is just a matter of time before someone, somewhere tries it again.
Heil Honey, I'm Home!, 1990
Cancelled after one episode (only the pilot was screened on the now-defunct satellite channel Galaxy), the show portrayed Adolf Hitler and Eva Braun living next door to a Jewish couple, Arny and Rosa Goldenstein, and centred on Hitler's inability to get along with his neighbours.
Quote: "I'm a very, very, naughty Hitler."
Absolutely Fabulous, 1993-2004
The series followed Patsy and Edina as middle-aged women who refuse to let go of the party lifestyle that they conduct in a public relations bubble.
Quote: Patsy: "The last mosquito that bit me had to book into the Betty Ford Clinic."
Till Death Us Do Part, 1965-75
The show centres on working-class racist Alf Garnett.
Quote: (Speaking to "Paddy-Paki") "If it wasn't for the colour you wouldn't know the difference."
Derek, 2012 onwards
Derek is a care-home assistant who, his creator Ricky Gervais insists, should provoke sympathy, but others have perceived the show as making cheap jibes at the disabled and mocking those unable to defend themselves.
Quote: Derek: "I hate it when anyone dies; they are always dying because they are old."
To be aired later this year by NBC in the US, the untitled show will feature Michael J Fox – who has Parkinson's – as a husband and father of three from New York City who is dealing with family and career challenges.
Critics said its depiction of the working class on an estate was crass.
Quote: "Get your stuff out quick, otherwise he'll have your stereo in his veins before you can say Dolby surround sound."
Waiting for God, 1990-94
Set in a fictional retirement home in Bournemouth, it focused on Diana Trent and her relationship with Tom Ballard, who has semi-feigned dementia.
Quotes: Tom: "Well, that's cheating, Jane. You can't rise from the dead if you haven't died."
Getting On, 2009 onwards
The show, set in the geriatric ward of a hospital, deals with issues in the NHS including lack of beds and communicating with non-English speakers.
Quote: "What do you mean they don't have any relatives? She didn't arrive from under a gooseberry bush." "She was found under a flyover."
Arrested Development, 2003-06
Broadcast on Fox in the US, the programme revolved around the members of the Bluth family and had incestuous undertones. In one episode two characters who are cousins kiss. They later find they are not blood relatives as one of their mothers was adopted.
Quote: "I was an analyst and a therapist: the world's first 'analrapist'."
The New Normal, 2012
Shown in the US, the show follows a gay couple in LA trying to have a baby. The couple meet a single mother who agrees to be their surrogate before her conservative grandmother tries to thwart their plans.
Quote: "The only thing I ever got from church was a lifelong complex about inferior abs. You stare at Jesus throughout puberty. That guy was ripped."