Lauren Ledford, from California, US, said she used the delivery app, Postmates, to order a pizza and assumed the $4 tip was included in the delivery fee.
But a week later, she found a 'threatening' note on her doorstep, saying he would rob her if she didn't tip him next time.
'If it turns out that delivery driver is me again, and you do not tip yet again, I’m probably going to rob you. I’m joking, but not really,' the handwritten note said.
'Who knows what a disgruntled delivery guy who can't afford to eat that day is capable of.'
Admitting to being high in his letter, the driver said 'I need your tip to stay toasty'.
After contacting police, Lauren shared a photocopy of the letter online to warn others.
'I am now terrified that this man could show up any day.'
Postmates has now reportedly suspended the driver, but Lauren said she still feels very unsafe in her own home.