After the fourth time Rodney muttered "Kill them all" while furiously scribbling notes John looked up from his book.
"Do I have to worry?" he asked mildly.
"No," Rodney said cheerfully, "it's for Jeannie."
That wasn't really reassuring. It must have shown on his face, because Rodney huffed. "Relax. I'm not helping her kill the neighbors. She wanted something to get the fruit flies out of her kitchen."
"Didn't you build a sonar repellent for that?" John remembered that show fondly: halfway through it had turned into a game of who could make the most Batman jokes.
Rodney grinned proudly. "Sold out. Besides, this is more fun."
John craned his neck to get a look at the notes. There seemed to be even more exclamation marks than usual. "Yeah?"
"Instead of driving them away, this thing will burn them instantly! It can be reconfigured for mosquitoes and ants, too. Hey, maybe I can include an option to kill Kavanagh's lice!" Rodney said gleefully.
John sat up straight. "You're building a laser death ray?"
"You're building a death ray and you didn't tell me?!"
"Um." Rodney briefly looked guilty as John grabbed the notes. "You can test the prototype?"
"You bet," John said, already distracted by the beautiful diagrams. "This cannot possibly be legal."
"Maybe not strictly speaking, but Jeannie's not going to tell anyone," Rodney said, unconcerned.
John felt a wide grin spread over his face. "You make me the best toys."
He wondered how many bugs this thing could kill.