once in a blue

Shortened version of"Once in a Blue Moon"

I travel there once in a blue

by Vista2Fit December 2, 2017

once in a blue moon

To do something very rarely, once in a while.

I don't usually hang out here, just once in a blue moon.

by Roboot February 1, 2007

once in a blue moon

To do something on a very rare occasion.

Stephan will come to the office once in a blue moon.

by yurmix February 20, 2018

Once you go blue, you can't undo.

The phenomenon in which a normal conversation turns blue, becoming so riddled with sexual innuendo that it's rendered nearly impossible to steer back in a non-pervy direction. Every innocent comment starts to become a dirty double entendre, until eventually the entire conversation turns into a complete smut-fest from which there is no return.

Girl: Ah, who doesn't love stripper zombies in Portland? That'd go down like Jesus on a velociraptor.

Guy: I have to admit, when I first read 'go down'... I had rather blasphemous thoughts.

~ten minutes later, during which this term is invented~

Girl: Hmm, this Urban Dictionary thing is quite fun. Something for the annals of history.

Guy: Two n's - one 'n' is bad.

Girl: Yeah, I always thought that 'annals' was an odd word.
It really could so very easily be another.

Guy: Terribly easily. So, how is the entry? ...Oh, Jesus!!!!

Girl: Once you go blue, you can't undo.

by The Terror Twins August 3, 2010