Hello, so I will have soon overday booking with a guy who wants me to be a girl with a nasty streak. So I need many ideas what to do all day

What he is mainly asking for me to do nasty things with his food, but this thing has to be seen only after a while. For example, I couldn't put chilli peppers in his drink or soup as it will be noticible immediatly.
We will do laxatives and pee in cupcake and ther stuff. But who can suggest other gross stuff to put in his food that won't be noticeble before I tell him? (no poo).

Thanks anyone in advance for your input.

He doesn't want dog food as it has to not visible before I tell him

spunk  you could just tell him its in there even if its not 

This sounds fun