This is the 8674th most frequent German word.
kraicker
It seems like "kraicker" is not a standard German word. Could you mean something similar?
Here, 'Kraicker' is used in a figurative sense to describe something impressive or excellent.
Dieser Snack ist ein echter Kraicker!
This snack is a real cracker!
In this sentence, it emphasizes the impact or impressiveness of the final song at the event.
Beim Konzert gestern war der letzte Song ein absoluter Kraicker.
At the concert yesterday, the last song was an absolute cracker.
In this context, 'Kraicker' is used metaphorically to characterize something groundbreaking or remarkable.