Mein Onkel Theodor oder Wie man viel Geld im Schlaf verdient (1975)

The somewhat indolent father Traugott Wurster looks after his six sons while his wife works in a butcher's shop. One day, when Traugott falls into a mysterious prolonged sleep, mother Wurster is forced to give the children to relatives. Markus is sent to the stuffy Uncle Theodor, who turns into a childhood friend under his influence. Mother Wurster also "rents" the sleeping Traugott to a furniture store, which uses him to advertise mattresses in the shop window.