When is a joke not funny? Answer: When it has been stolen.
In theory there is nothing stopping comedians copyrighting their jokes to try to protect them but the reality is very different.
They face a world where sharing content is all the rage, jokes are printed on the internet and whole performances are filmed and broadcast on websites - mostly without earning them a penny.
A search on YouTube for Lee Hurst turns up 25 clips including television and live performances by the comic.
Search for the winner of the 2008 IF Comedy Awards, David O'Doherty, and you will find around 100.
Comics also face the age-old problem of unscrupulous performers stealing other people's jokes and claiming them as their own.
Loki Mackay, manager of The Comedy Store in London, said comedians had little time for people who steal material in any form.
He said: "Borrowing jokes is theft and it is not condoned on the circuit.
"Good comics know their own material and each others and if people start using someone else's jokes, people will refuse to work with them and venues will refuse to book them.
"It is self-policing."
The venue, in central London, has taken some steps to protect performers by banning mobile phone use during shows.
Mr Mackay said: "We ask people to turn their phones off at the start of the show.
"If people are texting or talking on them we will take them out and give them a warning.
"Anyone caught filming will be kicked out."
Oliver Double, author of Getting the Joke - The Art of Stand-Up Comedy, said the theft of material became more of an issue with the rise of a more personal style of alternative comedy.
He said: "In the working men's clubs it was accepted that people stole material.
"The ethos was if someone told a joke it was anyone's to take.
"Also many of those comedians told jokes in the third person. Routines are more personal now."
He added that the rise of new technology had also changed attitudes.
He said: "Stealing material has become more unacceptable since the 1970s and 1980s. I can remember doing a gig in Sheffield in the 1990s and it was going to be filmed and almost all of the comics refused to be filmed.
"Then they were worried about it showing up on cable television and not being paid.
"Obviously now with the rise of the internet that paranoia is far more justified."