The Knicks weren’t ready for the adult trip.

Tom Thibodeau’s hot-and-cold squad went frozen in a 108-100 loss to the Hawks and was eliminated from the NBA Cup quarterfinals.

So instead of heading to Sin City for the semis, the Knicks next travel to Mickey Mouse territory, Orlando, to face the Magic on Sunday.

They deserve the kiddie rides after Wednesday’s dud at MSG.

The Knicks (15-10) were out-rebounded, out-hustled and perpetually more obsessed with the referees than their own struggles.

The Hawks (14-12), who next face the Bucks in the NBA Cup semis in Vegas, pounced in the second half as Trae Young again won an important night at MSG.

Jalen Brunson managed just 14 points on 5-for-15 shooting and was locked up by Dyson Daniels, a budding All-Defense candidate who hounded and cut off New York’s point guard at every pivot.

The Knicks shot just 26 percent on treys, 60 percent on foul shots and allowed 22 offensive rebounds, as exemplified by a five-shot Atlanta possession in the fourth quarter.

Young finished with 22 points and 11 assists.

The longtime enemy at MSG briefly was the target Wednesday of profane chants, the familiar, “F— Trae Young.”

But in the end — as the final buzzer sounded — the crowd booed the Knicks, not Young.

The defeat cost each Knicks player over $50,000 in prize money they would’ve received for reaching the semifinal, which would’ve been added to the $50,000 they got as quarterfinalists.

The Hawks shot poorly in the first half but the Knicks could never create enough separation to feel comfortable.

Atlanta chipped away until taking its first lead of the contest on Young’s trey midway through the third quarter.

The rest of the half was a Knicks misadventure and a Young triumph at MSG.

The previous time Young faced the Knicks in an elimination game, nearly five years ago, he buried the home team and finished the evening with a Broadway Bow.

But the Knicks were heavy favorites in Wednesday’s NBA Cup quarters and clearly felt comfortable facing the Hawks.

New York had an opportunity to chase the East’s top seed of the NBA Cup — which would’ve meant a showdown against the Celtics in the quarterfinals instead — but eased up down the stretch of the final group stage game to maintain the point differential for a Hawks matchup.

In the Magic game, the Knicks were up by 31 with six minutes remaining and won by only 15.

A victory by 37 or more would’ve meant a quarterfinals against the Celtics.

While Tom Thibodeau played it coy, Josh Hart basically acknowledged the Knicks were aware of the implications as their lead dissolved.

It was a smart move for a number of reasons, including that the NBA Cup doubles as regular-season games. Who would want an extra game against Boston on the schedule?

But it didn’t help the Knicks, who can cancel their Vegas plans.