The best life hack advice I ever got was from my first internship. It was at an engineering firm and as I was sneaking out the back stairwell for a cigarette (yes, I was a smoker for a brief period, shame on me) I ran into an engineer and he asked what I was doing, so I made something up and said I was running an errand. I returned his question, "what are you up to?"
Engineer: "I'm carrying a clipboard" Me looking confused. Engineer: "if you ever want to look busy, just carry a clipboard...."
Worked every time!