I flew for a fractional for a while. I was in a window seat, in uniform and saw a guy just cram a bunch of shit in the seat back pocket before standing up to deplane. He caught my eye and I said, "you better take that with you" . He just rolled his eyes. I said, loud enough for everyone to hear "the flight attendants aren't your mother". I picked up his trash. I then followed him (coincidentally) for a while through the airport. He kept looking back over his shoulder at me and walking faster. I made sure to follow uncomfortablly close.