The other day, I had a conversation that went like this:
"Could you sweep?"
-"Someone else is already sweeping."
"There's two brooms."
It "should" be "There are two brooms", but I would never have said that. Perhaps because "there's" is shorter without being as clunky as "there're"? Has anyone else observed this? Do you ever use "there's" when what you're referring to is plural?