1 cup of milk.

[Crutch]

 You have a jug of milk, and you need to measure out just one cup. How do you do this if you only have a three-cup measuring container and a five-cup container?

[new2turkey]

Fill the 3 cup container up, pour it into the 5 cup container. Fill up the 3 cup container and pour it into the five cup container until the 5 cup container is full... That will leave you with 1 cup left in the 3 cup container...

Did I win? 

[Crutch]

 

[new2turkey]

 

[hookedspur]

Fill the 3 cup container up, pour it into the 5 cup container. Fill up the 3 cup container and pour it into the five cup container until the 5 cup container is full... That will leave you with 1 cup left in the 3 cup container...

Did I win? 

:agreed:your fast.

[new2turkey]

Fill the 3 cup container up, pour it into the 5 cup container. Fill up the 3 cup container and pour it into the five cup container until the 5 cup container is full... That will leave you with 1 cup left in the 3 cup container...

Did I win? 

:agreed:your fast.

To be entirely honest, that's the only riddle I've ever been able to solve on my own