I had fresh coconut the last time I went to Hawaii. It’s a tough nut to crack.
Tough Coconut
Explanation
Explain Bear
Alright, listen up, buttercup. This joke is playin' on the fact that coconuts are hard to open, see? But it's also sayin' that Hawaii was a "tough nut to crack", meanin' it was a challenge or difficult. Get it? Of course you don't.