The idea: Set off a firework in the front yard of another student's off-campus home and smash some pumpkins.
The two freshman - Darby Dudley, 18, of Mason and Olivia Hudson, 18, of Okemos - invited several friends to come along for the ride in Dudley's mother's Cadillac sedan. Two fellow freshmen agreed.
"We were just bored," Dudley testified Wednesday at a hearing in 54B District Court. "Sunday night after Halloween, sitting in our dorm room. We wanted to, kind of, just do something fun."
Police arrested the four students within minutes of the explosion, which happened in the 400 block of Grove Street in East Lansing. All were charged with felony explosives charges and each previously faced up to 20 years in prison. Police found two devices, which an expert called "improvised commercial aerial display mortars" with three-inch fuses, inside the car.
In court Wednesday, Dudley, Hudson and 18-year-old Sasha Savage of Okemos said they intend to plead guilty to misdemeanor charges, and as part of their plea agreements, will not be sentenced to jail terms. They will face probation and community service.
The three testified at a preliminary hearing for Nikolai Wasielewski, 18, who now faces different charges of conspiracy and accomplice after the fact. They carry the same penalty as the original charges.
Assistant Prosecutor Diane Smith told Judge David Jordon she was amending the charges against Wasielewski.
The hearing, which will continue at an undetermined future date, determines if Wasielewski will stand trial. The Rossford, Ohio resident was in the car's back seat, when Dudley opened the passenger side window, and tossed what was described as a golf-ball-sized firework into the yard.
'Along for the ride'
When the device went off, the explosion could be heard a few blocks away at the East Lansing police station.
Wasielewski's attorney, Mike Nichols, said his client was simply along for the ride.
When Nichols asked Hudson if that was true, she said: "I invited him. He knew what was going to happen ...so yes, in that sense, he was along for the ride."
Dudley said she got the fireworks from her parents' house. They were left over from the Fourth of July, she said.
The two found by police in the car were larger than the one that exploded, she said.
3 inches in diameter
Michigan State Police Sgt. Scott Hasse, a bomb technician, testified that they were 3 inches in diameter. He said in Michigan only licensed commercial display artists are allowed to have the mortars. Modified versions with fuses, he said, are dangerous, and would cause serious injury or death if detonated near someone.
Dudley, Hudson, and Savage all testified that they were pulling a prank on a resident at the house they knew from Okemos High School.
Someone came up with the idea to cover the car's license plate - which according to testimony reads "I LOVE MSU" - with paper napkins. After the explosion and they were driving away, Wasielewski told them they should stop and remove the napkins, according to testimony.
One of the Grove Street home's residents, Michael Ogilvie, said there was no damage to the house or the yard. Ogilvie said he didn't feel harassed, terrorized or intimidated.
"I didn't think it was a big deal," he said.