Mum finds out son's been wanking on the job

Mum reads son's diary and finds a disturbing entry where he describes his liking for wanking into the soup at the Chinese buffet restaurant he works at. That's sick! Desperate for help, she turns to Yahoo Answers. Thank god, he isn't working in my favourite restaurant. From Yahoo Answers:

Well, I came across his diary this morning and had a peek. Stuart wrote that he likes to masturbate into the bucket of soup they have in the fridge at the restaurant. He wrote that he sneaks the bucket of egg drop soup into the bathroom in the back and will masturbate into it.

I'm not sure what to do. He's a sweet boy, and this job has been wonderful for him. I don't want to say anything to him because I don't want to embarrass him and I don't want him to lose his job.

And besides, I don't think anybody would notice anyway because egg drop soup has them white stringy things floating around in it anyway. What people don't know won't hurt em. What should I do?