On a night when the Denver Nuggets should have been celebrating a much-needed victory over the Portland Trail Blazers, the franchise continued to struggle with off-the-court issues when an April Fools' Day joke sparked anything but laughter.

During Denver's 109-92 victory Thursday, a former Nuggets ball boy, Laquan Johnson, got into the club's locker room, took Kenyon Martin's car keys and filled the player's Range Rover with buttered popcorn. The car had a white interior.

Martin discovered the damage as he was about to exit Denver's Pepsi Center. At the time, he had no idea who had pulled the prank. Angered, he went back to the locker room spewing profanities and threats at teammates and other members of the organization.

"That ain't no [expletive] joke," Martin said. "I'm going to find out who did it ... put my [expletive] hands on one of y'all. I'm going to put my hands on whoever did it. You better believe that. It's [expletive] personal. You better believe it."

Martin, who has missed 15 games with a torn patella tendon in his left knee, threatened to boycott the postseason if he did not find out who was responsible.

"How 'bout if I don't play in the playoffs until somebody tells me who did it," Martin said more than once.

Martin stormed in and out of the locker room several times, and a person close to him said his anger was not over the prank, but over the fact that someone could go into his pocket and take his keys during a game. Realizing the culprit had to have access to the private code for the team's gated parking lot, he assumed members of the organization either pulled the stunt or assisted in it.

"The fact that no one saw it or had anything to say about it -- not security, not the equipment manager," a person close to Martin said, explaining the player's anger. "Somebody had to see it. He was wondering how the organization let something like that happen. What if the kid had really wanted to do something evil?"

Later, Martin found out Johnson, the former ball boy who is now the driver for teammate J.R. Smith, was responsible. Johnson apologized to Martin and agreed to pay for the damage to his car.

"It was just an April Fools joke that went horribly wrong," said a member of the Nuggets organization who spoke on the condition of anonymity. "The kid thought it would be funny and it wasn't. Kenyon was back at practice today and everything was fine between him and his teammates."

The episode was the latest in a string of distractions Denver has had to deal with lately. Once regarded as the Western Conference's top challenger to the Los Angeles Lakers, the Nuggets have all but fallen apart down the stretch.

With Martin out and coach George Karl missing games while getting treatment for throat cancer, Denver had lost five of six games before defeating Portland. That stretch dropped them from the second seed to the fifth seed in the West.

Martin, who cannot guarantee he'll be healthy for the playoffs, said before Thursday's game that he hopes to return for the last regular season game or two.

Chris Broussard cover the NBA for ESPN The Magazine.