There weren't enough paper towels.
Colby worked this out quickly enough. Trying to wipe coffee off of paperwork, when the paper towels were already mostly wet, just left brown smears across Don's neat handwriting.
Halfway through, Colby gave up, put the paper cup back on top of the paperwork, and dumped the towels in the trash.
Though this wasn't Colby's fault. Charlie had obviously left the cup on the stack of Don's paperwork halfway through a conversation, or a math demonstration, or something, and then clearly his brain had forgotten about it, and wandered his body away somewhere else.
The cup had rested forlorn, and forgotten, for a few hours, and then clearly protested its abandonment, by leaking all over the damn place.
Colby managed, just about, to block the view of paperwork with his own body, possibly getting splatters of cold coffee on the back of his shirt for his trouble.
Don was hanging in the doorway, serious expression on his face.
"Hey, Colby, you seen Charlie?" Don looked perplexed.
The last time Colby had seen Charlie he'd been drawing something that didn't so much look like math, as complicated battle tactics, on one of the boards in garish yellow pen.
When he'd questioned - no when he'd made the mistake of questioning, there'd be an explanation. Which involved a lot of pointing, and long words, and then finally a laugh, and yellow marker on his nose.
Colby had managed to escape with his dignity.
Though the sound of laughter had followed him back to his desk.
He shook his head. "No, no, not for a while."
"He didn't seem to be acting funny to you?"
Charlie always seemed to be acting funny to Colby, Colby suspected Charlie lived on an entirely different scale of normal to him. He tried to think of a polite way to tell Don that his brother, may in fact, be the anti-christ.
There was really no way for that to go over well.
He shook his head instead.