In the classic 1930 film Der blaue Engel (The Blue Angel) by director Josef von Sternberg, the young actress Marlene Dietrich sings a song by Friedrich Hollaender with the lyrics: 

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Ich bin von Kopf bis Fuß auf Liebe eingestellt
Denn das ist meine Welt und sonst gar nichts

This is a good example of the noun der Kopf used in an idiomatic context. Many of the idioms using der Kopf in German are identical — or nearly so — to similar sayings in English.

Die Königin gab sich größte Mühe, ihn zu trösten: „Kopf hoch!“ 

The Queen did her best to comfort him: "Head up [Chin up]!"

Captions 33-34, Märchen - Sagenhaft - Die Prinzessin auf der Erbse

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In English it's common to say "hold your head up" to help comfort somebody, a British English equivalent being "chin up."  

Hiroshi Kajimoto hat den traditionellen Aufbau des Schirms nun auf den Kopf gestellt.

Hiroshi Kajimoto has now turned ​​the traditional construction of the umbrella on its head.

Captions 6-7, Erfindung aus Japan - Der verkehrte Regenschirm

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Thus the figurative meaning of "turning something on its head" is similar in German.

Ich habe doch Augen im Kopf!

I have indeed got eyes in my head!

Caption 60, Alexander Hauff - Showreel

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Most of us, of course, have eyes in our head, but the figurative meaning here is the same as in English: "I can see that" or "I'm not blind."

But there are some idioms using der Kopf that would sound very odd indeed if translated literally to English:

Ach, mach dir keinen Kopf [Umgangssprache], Lothar.

Oh, don't make yourself a head [slang, don't worry], Lothar.

Caption 36, Großstadtrevier - Neben der Spur

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This is similar to the predominantly British English expression "don't bother your head."

... weil da jeder Spieler schon seinen eigenen Kopf hat.

...because there every player already has their own ideas [literally: head].

Caption 31, Eishockey - Erich Kühnhackl

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While it's obvious that — short of some terrible disaster — everyone "has their own head," it's used here in a context similar to "headstrong" or "willful."

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Further Learning
Watch Marlene sing the song "Ich bin von Kopf bis Fuß auf Liebe eingestellt" in this video clip from the original 1930 film, then see if you can accurately translate the lyrics quoted at the start of this lesson. You can also go to Yabla German and find some more examples of der Kopf used in other contexts.