what does "get a wild hair"mean?
“I got that, loud and clear,” Eli agreed.
“But in this case, none of it fits. Duncan wasn’t an idiot, and he wouldn’t have met the guy he was shadowing alone, in a deserted area. Unless he got a wild hair to go to the lighthouse at night in the middle of a storm, he went to meet someone and most likely someone he knew. And someone killed him. You’re alibied, and there’s absolutely nothing to indicate you and Duncan ever met or spoke. Nothing to indicate you hauled your butt from Boston, where it’s confirmed you were when Abra Walsh was assaulted here in this house, then arranged to meet Duncan, killed him, then hauled back to Boston to toss his office, his apartment, then hauled back here again. Nobody’s buying that.”
“Wolfe—”Q2:what does "where it’s confirmed you were"mean?

Question

what does "get a wild hair"mean?
“I got that, loud and clear,” Eli agreed. 
“But in this case, none of it fits. Duncan wasn’t an idiot, and he wouldn’t have met the guy he was shadowing alone, in a deserted area. Unless he got a wild hair to go to the lighthouse at night in the middle of a storm, he went to meet someone and most likely someone he knew. And someone killed him. You’re alibied, and there’s absolutely nothing to indicate you and Duncan ever met or spoke. Nothing to indicate you hauled your butt from Boston, where it’s confirmed you were when Abra Walsh was assaulted here in this house, then arranged to meet Duncan, killed him, then hauled back to Boston to toss his office, his apartment, then hauled back here again. Nobody’s buying that.” 
“Wolfe—”Q2:what does "where it’s confirmed you were"mean?

Answer

A#1: Ok so "get a wild hair" is a American/English expression that refers to something you do that's not normal for you. For example, If you normally eat sushi everyday for lunch and decide that today you want a steak. We sometimes call that having a wild hair. Sometimes it can have a vulgar extra few words on the end of the sentence "up your ***" is common where I am from. A#2: "where its confirmed you were" means that The police or whoever is talking can prove that person was at a specific location at that time.