If it’s a “window of opportunity”, shouldn’t opportunity tap
instead of knock?
note: recently all my windows of opportunity have been double-paned: I’m insulated against that stuff, I guess.
Today I told students that I threw a pen really hard into the air and it’s stuck into the moon now. They found that one easier to believe than the frisbee that I threw really hard and hit me in the back of the head an hour later.
(I can’t really lie on the spot … I shift around a bit when I tell them)