They were walking quickly on the curb of a busy street when John shouts urgently "Sherlock, wait!"
Impatiently, the detective stops and turns to look John, frowning "What?"
The doctor, pointing at the building, explains "You're going to walk under a ladder and..."
With a small shaking of his head, the detective impolitely interrupts his friend "Come on John! You're a man of science, don't tell me you're..."
Not acknowledging Sherlock brusqueness, John continues before getting interrupted all over again "But Sherlock, it's not that..."
"You know where this all superstition come from?" the git laughs at the inanity of humanity "From the breaking of the perfect trinity cause by a ladder when it's leaning against a wall!" Pointing the sky he chuckles at his friend credulity. "The Christian Trinity of the father, son and whatever. You went to war and you are afraid of walking thru a TRIANGLE!"
"Yes, but maybe if you..."
"Are you afraid that I'm going to get bad luck because I angered a God? That I'm going to invoke the Devil!" As Sherlock rolls his eyes before going straight for the ladder, a big bucket of soapy water fell from the top of it... directly on Sherlock's head. The clumsy windows cleaner apologize, but it was too late as the detective curls, as well as his beloved wool coat, were already soaking wet.
Smiling, John walks by his stunned friend, doing a theatrical swerve to avoid the water on the sidewalk. "Look like God didn't like your comment after all..."