Ron Allus peered around the corner of the darkend corridor. "It's clear. Let's go."
He crept around the corner, Patrick Daver right behind him lugging the heavy bag he'd been given. "Are you sure this is okay?"
Patrick was a newbie, needed to be broken in. "Of course it's not okay. That's the whole point. It's a great tradition of the University that, on the week of their graduation, each senior has to pull a major prank on one of his or her professors. Graduating senior. That's me."

"But I'm an incoming freshman."
"Yeah, it is an honor to be chosen, isn't it? Trust me, this is part of the tradition. Someday, it'll be your turn."
Patrick didn't look convinced. "If I live that long. Now, are you going to tell me what we're doing?"
"We're going to set a little trap in Professor Vander's office. He's one of the part-time instructors, so we have to have our prank set for him. Next time he makes one of his irregular visits, 'bam!' ''
Patrick looked nervously at his shoulder bag. " 'Bam?' We aren't going to blow him up, are we?"

"Of course not. Not literally anyway. Nothing more than a few small shaped charges for artistic effect." He had Patrick put the bag down in the corridor outside Vander's office. "You see, Vander let a few of us seniors in on something he's planning on trying to patent. It's called aerogel."
"Aerogel?"
"Yeah," Ron grinned. "It's a rapidly expanding, extreamly sticky gel. Very strong at holding things in place, but short-lived."
Patrick again glanced at the bag. "So that's what's in there."
Ron reached into the bag and pulled out a canister with an electronic device attached to the top. "Not quite. I've been exploring the characteristics of aerogel, trying to improve it. This is what I've come up with so far. Expands even more rapidly, could be just as strong, and indefinately stable. Unfortunately, the expansion ratio is much smaller than the professor's aerogel."
He shook the canister. "But this is enough to fill Professor Vander's office solid. Unlike his aerogel, mine's translucent, like solid smoke." He removed a bag of tiny silver disks from the larger duffel. "As an added bonus, I'll rig charges just big enough to toss all his furniture into the air just as the stuff hardens."
Patrick's eyes widened. "Where did you get those?"
Ron laughed. "Don't worry, kid. They're homemade, and they wouldn't even injure a grasshopper."

Ron used a hacked keycard to open the door. "Okay, all you have to do is stand guard while I set things. Got it?"
Patrick nodded. Ron slipped inside, sat the canister in the middle of the floor, and started placing the little disks under all the furniture legs. He was almost finished when he heard Patrick's voice hissing in a loud whisper from outside. "Somebody's coming!"
Ron looked around. All the furniture was done, and he'd even placed disks to toss some stacks of paper into the air as well. All he had to do was place the trigger, and he could do that on the way out.

He sat the little motion detector on the floor in front of the door. He didn't want Vander to actually get inside. It would be triggered as the door started to open.
"It's Vander! Get out!"
Ron sighed angrily, fumbled with the trigger, and sprinted for the door, accidentally stepping on the little box as he did.
There was a loud "pop." Ron was first tossed headlong through the door, then stopped suddenly, as through by a great hand. He hung in mid air, his body parallel with the floor.

Patrick sat on the far side of the corridor looking at him in horror.
Ron looked back into the room, and saw the lower half of his body imbedded in the aerogel.
This is very embarrassing, he thought.
He looked up at the man approaching from down the corridor, and put on his best brownnosing smile. "Good evening, Professor Vander! What brings you out at this hour?"