With his memoir, ‘Spare,’ which finally hit bookstores around the globe on Tuesday, Prince Harry cements his place as the world’s least predictable living royal — a chaos agent of the most interesting kind.

The book is full of stories that can sound absolutely ridiculous, but they often open a window onto the mind of the estranged Duke of Sussex.

In one from January 2016, Harry, a “Friends” fanboy, found himself in Los Angeles, his future home turf, with a couple of mates.

He was introduced to “proper tequila, fancy schmancy tequila, and I was schooled in all the many ways of drinking it.” The next day — no hangover, thank you — they went to the house of Courteney Cox, who was friends with the girlfriend of one of his buddies.

“As a Friends fanatic, the idea of crashing at Monica’s was highly appealing. And amusing. But then … Courteney showed up.” Would they have to leave? Courteney said no, of course not. Then she invited more people over, and the party began.

Three or four tequilas into the festivities, Harry finally learned that the familiar-looking guy he’d been talking to was Will Arnett, the voice of Batman in “The Lego Movie” and its sequels. So of course he begged Arnett to do it. Do the voice. “He shut his eyes. He wanted to say no, but he didn’t want to be impolite. Or else he recognized that I wouldn’t stop.” Then — “Hello, Harry,” said the voice of Batman, tickling the prince to his core.

Will then led them to a fridge containing, among other things, chocolates infused with mushrooms. Yep, those kinds of mushrooms. The actor grabbed a soft drink. Harry and his mate indulged.

Later, when Harry went to the bathroom, a trashcan — the kind with a foot pedal to open it — suddenly became a head, then smiled at the prince after he stepped on the pedal. “I laughed, turned away, took a piss. Now the loo became a head too. The bowl was its gaping maw, the hinges of the seat were its piercing eyes. …. I finished, flushed, closed its mouth.” He left the bathroom giggling.