expression
do not turn upside down; this side up
A fixed phrase printed on parcels or boxes to indicate that the contents should be kept upright. Often seen on shipping labels.
箱の側面に「天地無用」と書いてある。
"This side up" is written on the side of the box.
A yojijukugo combining 天地 (heaven and earth, i.e., top and bottom) and 無用 (useless, unnecessary), literally meaning 'top and bottom are unnecessary', i.e., do not turn upside down.