'Hmm. Well, we'll have to hope you turn out to be good at something else, won't we.'
'What have you done for starter? Good heavens, I didn't believe that people still serve avocado.'
'Wildflowers, do you call them? A can of weedkiller's what this place needs.'
It's very easy to be churlish, but remember this: firstly, it makes people hate you, and, secondly, it reveals you to be a churl.
Still, if you believe that spreading unhappiness is a worthwhile return for a moment's imaginary triumph then I suppose that's the way to go.
Thing Not To Do Today: be a churl. A churl is a surly ill-bred person (ill-bred = no manners). Churl used to mean a farm labourer. It comes from the Old English ceorl, and is related to the Greek gerōn, old man