Its a tough one. My last guess is men behaving badly.
Sitcom Giveaways Page 3
Quote: Definitely Tarby @ 5th December 2018, 5:50 PMIts a tough one. My last guess is men behaving badly.
Sorry, that's not right.
If Chappers also wants to give up now, I'll tell you the answer.
Absolutely Fabulous?
Quote: Chappers @ 5th December 2018, 6:32 PMAbsolutely Fabulous?
No, that's not right.
Porridge
Quote: Definitely Tarby @ 5th December 2018, 6:47 PMPorridge
Tarby has got it!!!!!
........................................................................................
"I've just realised we're both the exact opposite of Mr Humphries."
"Well, that's a relief."
ANSWER: Porridge.
EXPLANATION: at the time of Fletcher's and Godber's imprisonment, Mr Humphries was an iconic sitcom character famous for his frequent cheery announcement "I'm free!"
Godber never coped well with life in prison and would often dwell upon the unhappiness of his condition. With the image of Mr Humphries in his mind, he says "I've just realised we're both the exact opposite of Mr Humphries." meaning that he and Fletcher lead a far from cheery life and are most certainly not free. They are, in fact, the exact opposite of free: they are literally prisoners.
Fletcher misunderstands Godber's remark and thinks it refers to Mr Humphries' unashamed effeminacy which, by the logic of the 70s, meant raving homosexuality.
Fletcher thinks that Godber is confirming that both he and Fletcher are totally straight and very masculine men (i.e. the exact opposite of being effeminate gays). Clearly, to a 1970s mildly homophobic man like Fletcher, it would be extremely distressing to find himself having to spend most of his days and all of his nights locked in a cell with a gay man.
Accordingly, he replies, "Well, that's a relief."
Hurrah 
That's exactly how I pictured it even down to the exchange being between Godber and Fletcher. I can see what you mean because that would have got a laugh. It's gently mocking camp men but in a cheeky, Delboy type way rather than a dislike to that lifestyle.
I don't have one yet so the next person to post one can be considered to be taking my go along with my compliments and a free gin and tonic.
Quote: Rood Eye @ 5th December 2018, 7:47 PMTarby has got it!!!!!
........................................................................................"I've just realised we're both the exact opposite of Mr Humphries."
"Well, that's a relief."
ANSWER: Porridge.
EXPLANATION: at the time of Fletcher's and Godber's imprisonment, Mr Humphries was an iconic sitcom character famous for his frequent cheery announcement "I'm free!"
Godber never coped well with life in prison and would often dwell upon the unhappiness of his condition. With the image of Mr Humphries in his mind, he says "I've just realised we're both the exact opposite of Mr Humphries." meaning that he and Fletcher lead a far from cheery life and are most certainly not free. They are, in fact, the exact opposite of free: they are literally prisoners.
Fletcher misunderstands Godber's remark and thinks it refers to Mr Humphries' unashamed effeminacy which, by the logic of the 70s, meant raving homosexuality.
Fletcher thinks that Godber is confirming that both he and Fletcher are totally straight and very masculine men (i.e. the exact opposite of being effeminate gays). Clearly, to a 1970s mildly homophobic man like Fletcher, it would be extremely distressing to find himself having to spend most of his days and all of his nights locked in a cell with a gay man.
Accordingly, he replies, "Well, that's a relief."
If he was slightly meta and was into analysing the heterosexuality of his cell mates? Fletcher was an alpha male, Godber less so.
Then it must be my turn. What sitcom is this line from? Basil: Polly have you seen Manuel?
If that's too hard then:
'I found one of your bus receipts on the floor'
'Really, which number?'