No, this one has nothing to do with an episode of How I Met Your Mother. Instead, it refers to a rather controversial line of dialogue from Don back in season 3: The window for this apology is closing. Hardly seems like a line to raise eyebrows, but thats exactly what it did in linguistic circles. It has been noted that using the term window in a metaphorical sense did not actually start until the 1970s. Further proof that Don truly is a visionary.