I'm going to wash my hairs.The first seems to be pretty limited these days and second is widespread beyond here, surely.
Let's have some beers.
Surely related is that some things which are plural for most English speakers are singular here:
a scissor(s)These are really common around these parts. The whole set may reflect immigrant language influences, as the Wisco English crew is exploring in some current research. Last night, I heard a good one, having dinner with a group of Madisonians:
a nail clipper
There's a roll of paper towel on the shelf.The meaning was quite clear: A roll of paper towels. Following up, it wasn't a performance error or anything, but a normal-sounding form to those present. When I tried to get the group's reaction on things like a clipper and whether they say a scissor or a scissors, I got some surprises, like one speaker (Wisconsin born and bred) who reported a pair of scissors but then spontaneously used a nail clipper in talking about the issue.