What does "going blue" mean?

I'm familiar with the expression to feel blue, but I recently stumbled upon the expression to go blue on two different websites in one week.

Vork from The Guild goes a bit blue

Source: http://blogtown.portlandmercury.com/BlogtownPDX/archives/2011/03/24/in-which-i-discuss-the-topic-of-web-series-with-my-head-on-my-desk

The second site:

Our panel from ECCC last weekend. It went a bit blue. Thanks Wil Wheaton, hehe.

Source: http://felicia.posterous.com/eccc-11-the-guild-panel-part-1

Usually I can track down the meaning of expressions myself, but since Google isn't being very helpful I'm turning to you guys. I'd also like to know if this expression is used widely across the English-speaking world or if its use is limited to certain regions.

(Please forgive me if my English isn't flawless... I'm a 19-year-old non-native speaker.)

Solution 1:

This is in reference to a 'blue movie', a euphemistic term for a pornographic film.

It has since been toned down somewhat and phrases like a bit of blue can be used to say that something is 'adult' in nature. Often this includes dealing with sexual material but doesn't necessarily mean visually pornographic; a comedian who tells jokes with a sexual theme could be called 'a bit blue'.

going a bit blue then would mean that the programme/character in question is normally 'clean' but has begun to include more adult themes.

It would appear that the term has been used thus since the early 1800s, originating in Scotland, though a clear connection between the colour and the connotation has not been settled on.

N.B.: Bolton comedian Peter Kay is famous in England and well known for his family friendly stand up material. In his shows he will occasionally tell a joke with some sort of subtle sexual reference or other 'adult' theme and then follow the joke by saying 'a bit of blue for the dads there'.

Solution 2:

"Blue" humor is a type of humor that is dirty and offensive. So if a performance or public event "goes blue", it means that much of the humor is profane.

From Wikipedia:

Blue comedy is comedy that is off-color, risqué, indecent or profane, largely about sex. It often contains profanity and/or sexual imagery that may shock and offend some audience members.

"Working blue" refers to the act of performing this type of material. A "blue comedian" or "blue comic" is a comedian who usually performs blue, or is known mainly for his or her blue material. Blue comedians often find it difficult to succeed in mainstream media. Topical musicians may use blue comedy both in their commentary between songs and in the lyrics to their songs.