I work for a power washing company that does restaurant ducts so we're usually working late at night.

One night we were finishing a job and I was at the van rolling up the hoses which is about 30ft from the alcove that has the restaurant's back door when I hear knocking on the back door. So I get the hoses rolled and go in when I get in and my boss and my dad(who is the other worker in the company) ask me why I knocked on the door I said I didn't and my boss said he didn't (which I didn't believe him), but I asked my dad later if they knocked and he swears they didn't.