Pretty sure it's a reference to a Simpsons episode where Ralph becomes obssessed with Lisa after she gives him a valentine's card out of pity. He assumes they're dating and keeps harassing her. At one point he shows up at the house and Lisa tells homer to make up some excuse to get him to leave. The parent poster's comment was the excuse.
I kind of hate that I remember that. I haven't watched the Simpsons for who knows how long but that shit's just burned into my brain from how many times I watched it as child.
