" once in a lifetime "

 [ "once in a lifetime" ]

1: something so incredible i happens once in a lifetime, regardless of deserving

  * e.g.,  ... Once in a lifetime, uttelry impossible. 

 [ "Once in a Lifetime" ]

1: Amazing song by Talking Heads

  * e.g.,  ... Letting the days go by/let the water hold me down 

 [ "Once in a Lifetime" ]

2: If you can listen to this song or Psycho Killer and not love it, I think Miley Cyrus may be the kind of music your looking for.

  * e.g.,  ... Letting the days go by/water flowing underground 

 [ "Once for a lifetime opportunity" ]

1: When the chance arises to do something illegal you've always wanted to but you unfortunately know it would likely get you a lifetime sentence in prison.

  * e.g.,  ... Jim: "Hey I was stopped at a pedestrian crossing and then of all people I see my boss, walking out in front of me. I could've flattened him." 

 [ "once in a lifetime" ]

1: An experience so rare that it often happens only once in a person's entire lifetime. Basically, it can be seen as something that might happen only once in roughly 60 years or longer.

  * e.g.,  ... For some, a trip to Disney World is a once in a lifetime experience. When a friend moves long distance, getting together with that friend for a dinner and a movie is very commonly a once in a lifetime experience. Getting married is a once in a lifetime experience.