"Sherlock's bored again." John said walking into the Doctor's office. The Doctor sighed and looked up at John who had stopped in the doorway.
"Have him do an experiment."
"All his experiments are in the waiting process." John's phone beeped, he checked it and rolled his eyes "He says that he would love to experiment on you."
"Not gonna happen."
"That's what I thought you were going to say."" John turned away but before he could leave his phone went off again. He checked it and turned back to the Doctor, who was deeply involved with his own experiment. "Doctor?"
"Sherlock wants to know what you're working on."
"Tell him that he wouldn't understand."
"Try me, there isn't much I don't understand." Sherlock said scaring both the Doctors. The Doctor sized him up then spouted a bunch of techno babble that John didn't have a hope of understanding. When the Doctor stopped talking, Sherlock nodded and sat down across from him and pulled a microscope close to him. For ten minutes no one moved. Then John spoke
"Right then, I'm going to leave and take a nap." No answer. John decided to mess with them. "Then I'm going to dye my hair purple." Nothing. "Maybe I'll blow up Earth while I'm at it." Still nothing. "After that I think I will go mess with Sherlock's experiments while eating a banana." Both heads shot up.
"You wouldn't." They said in sync
"Wouldn't I?" John said smiling, before he turned and walked away.
"He won't." Sherlock said and they both went back to work, completely forgetting about John. Until half and hour later a loud explosion snapped them from their reverie. Together they ran to where the sound had come from. When they arrived they found a very pleased, very dirty, and very smiley John eating a banana while watching Sherlock's experiments burn. From that day on Sherlock and the Doctor never doubted John again.