Looking for a phrase that means ...

[dervast]

Hello I heard a phrase last time on a movie that I am trying to remember. The phrase means lets do this only for this time and it was like:

Let's do this just/only for once.
Let's do this just/only once.


Which one do you think is correct?

Best Regards

 

[bds51]

Hello Dervast,
The expression could me "one time only"

 

[billmcd]

You will hear anything in a movie but don't use "for" as in the sentence you presented.