verkacken
to screw up
(Colloquial, vulgar) To do something completely wrong, to ruin a task or situation; to make a big mistake.
Ich habe die Prüfung total verkackt.
I totally screwed up the exam.

to screw up
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to screw up
(Colloquial, vulgar) To do something completely wrong, to ruin a task or situation; to make a big mistake.
Ich habe die Prüfung total verkackt.
I totally screwed up the exam.

This word is very colloquial and is felt to be crude or vulgar. Use it only in informal situations with friends and avoid it in written language or formal conversations.
Mist, ich glaube, ich habe es total verkackt.
Damn, I think I totally screwed it up.
The verb consists of the prefix 'ver-' and the vulgar verb 'kacken' (to shit). The prefix 'ver-' expresses here that something is done wrong or ruined, which reinforces the negative meaning.
Er hat die letzte Frage verkackt und deshalb die Prüfung nicht bestanden.
He screwed up the last question and therefore did not pass the exam.
'Verkacken' (to screw up) is mostly used transitively with an accusative object that describes what was ruined. The fixed phrase 'es verkacken' (to screw it up) is also very common.
Ich habe die Präsentation komplett verkackt.
I completely screwed up the presentation.
to succeed
'gelingen' and 'verkacken' are strong opposites. 'gelingen' means that something turns out well or is successful. 'verkacken' means that someone does something completely wrong or ruins a situation. Style is also important: 'gelingen' is neutral, while 'verkacken' is vulgar and colloquial. You should use 'verkacken' only in very casual conversations, not in formal situations.

Wenn du ohne Vorbereitung ins Gespräch gehst, verkackst du vielleicht die Chance.
If you go into the conversation without preparation, you might screw up the opportunity.
In der Schule gelingt Lisa die Präsentation besser als erwartet.
At school, Lisa's presentation goes better than expected.