spinnen
to be crazy
Colloquial for being crazy, having nonsensical ideas, or behaving unreasonably.
Du willst ohne Jacke bei der Kälte raus? Du spinnst ja!
You want to go out in this cold without a jacket? You're crazy!

to spin / be crazy
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to be crazy
Colloquial for being crazy, having nonsensical ideas, or behaving unreasonably.
Du willst ohne Jacke bei der Kälte raus? Du spinnst ja!
You want to go out in this cold without a jacket? You're crazy!

'Spinnen' (to spin / be crazy) is a strong, irregular verb. The past forms are 'spann' (simple past) and 'hat gesponnen' (perfect tense), and they apply to all meanings of the word.
Früher spann meine Großmutter ihre eigene Wolle.
In the past, my grandmother spun her own wool.
The meaning of 'spinnen' (to spin / be crazy) is easy to recognize from the subject or object. A spider spins a web, wheels spin on ice, and people spin wool or weave intrigues.
Die Spinne in der Ecke hat ein großes Netz gesponnen.
The spider in the corner spun a large web.
In the meaning 'verrückt sein' (to be crazy), 'spinnen' is very colloquial. It is used among friends or in informal situations, but not in formal conversations or texts.
Du willst bei diesem Sturm wandern gehen? Ich glaube, du spinnst!
You want to go hiking in this storm? I think you're crazy!
The colloquial meaning is often used as a direct question ('Spinnst du?' — Are you crazy?) or as an exclamation ('Du spinnst doch!' — You're crazy!), to express surprise or lack of understanding about someone's behavior.
Was, du hast deinen Job gekündigt? Spinnst du total?
What, you quit your job? Are you completely crazy?
In the figurative meaning of devising a plan, 'spinnen' (to spin) is used almost exclusively in the fixed expression 'eine Intrige spinnen' (to weave an intrigue). It describes the secret and complex planning of a conspiracy.
Die beiden Konkurrenten spannen im Geheimen eine Intrige gegen den Firmenchef.
The two competitors secretly wove an intrigue against the head of the company.
to play
'verrückt spielen' and 'spinnen' can both express that something is not normal. The important difference is in their use. 'Verrückt spielen' is used mainly for devices, body parts, or systems when they suddenly stop working properly. 'Spinnen' is used colloquially more for people when they have nonsensical ideas or behave unreasonably. The words can be confused because both are colloquially connected with 'verrückt' (crazy). Remember: 'Der Computer kann verrückt spielen' (the computer can act up), but 'ein Mensch spinnt' (a person is acting crazy).

Du spinnst doch, wenn du bei diesem Sturm mit dem Fahrrad fahren willst.
You're crazy if you want to ride your bike in this storm.
Seit dem Update spielt mein Handy verrückt und geht ständig aus.
Since the update, my phone has been acting up and keeps turning off.