I use britches all the time. When I have to undress a patient to work on a wound, I usually call the pants 'britches' and the underwear/depends are 'drawers' They all know what I mean and I like saying that. I've got more, I'm sure this thread will remind me of many.
edit to add: chesterfield for couch. And verandah for the porch. I don't know if those are still common in Canada but I learned them from my grandma, who would be 115 or so if she were still alive.