Food cart and unhealthy habits

I am at a sports ground, there is a Coffee cart run by a lady. Her son (about 12 years old) is with her.
Mum is sitting down, her son is making himself a drink, using the stainless steel milk jug.
He pours the contents into a cup then licks the spout of the jug. Does not wipe it clean. 😋
Mum does not see this and the jug is ready for the next customer. 🙄