I’m sure there’s a knack to using knock in a post for Microblog*ember

@cn Well, it’s the name for the clicky part of a pen, so you could have said something like: “I prefer pens with a knock over pens with a cap, and I prefer them both over pens with a twist.”

Also?… it’s the first two words of every knock-knock joke. I don’t mean to knock your usual wit, so you must be knackered to have missed that.