Apples:
John frowned as he rummaged through the fridge. "When is the last time you cleaned out in here?"
"Never," Sherlock called back. "I'm hoping that one day the mess will simply wrap itself around in some time/space warp and be clean again."
"Good luck with that," John muttered as he inspected what was once a head of lettuce. "Ah." An apple. That looked safe enough. It must have recently been placed in there.
He took a bite, wandering back out into the main room. "Want anything?"
"Spit it out."
"What?"
"The apple. It's injected with arsenic."
"Oh God…is NOTHING safe?"