I've been in a similar situation a couple of times before, and I always make a point to apologize directly to the child for their parent's 'terrible behavior'. That usually gets the shitty parent really riled up, which is always good for a laugh.
Madness string 98197
Given the pain I just felt after rubbing my eyes after cutting peppers, I can tell you MY EYES ARE REAL. VERY, PAINFULLY, REAL. Yes, eye, you can stop crying now. It's fine.