You should not leave food unattended
Sam is birdwatching while eating lunch in the park when he receives a phone call.
Sam wants to answer the phone call.
Sam answers the phone call while remaining seated on a bench.
Sam leaves his food on the bench to get up and walk around while talking on the phone.
Sam is able to finish enjoying his lunch.
A bird swoops down and steals Sam's lunch, so he has nothing left to eat.