1
general::
With the top facing upward, as in Please keep the box holding the china rightside up, or He turned his cards right-side up. [Early 1500s]
American Heritage Idioms
2
general::
Phrase(s): right side up
with the correct (top) side upwards, as with a box or some other container. • Keep this box right side up, or the contents will be crushed. • Please set your coffee cup right side up so I can fill it.
McGrawhill's American Idioms And Phrasal Verbs