Funny idea to escape prisons

Two convicts are locked in a cell. There is an unbarred window high up in the cell. No matter if they stand on the bed, table or one on top of the other they can’t reach the window to escape.

They then decide to tunnel out.  However, they give up with the  tunneling because it will take too long.
Finally one of the convicts figures out how to escape from the cell.

What is his plan?