In the days of Sesame Street prior to Elmo, back when Mr. Hooper was still alive and Mr. Snuffleupagus was still invisible, almost all of the skits or animations in a given episode were tied to a specific letter or number. In the case of X, there was this mysterious, kind of creepy sounding (to a little kid) song called X Marks The Spot. This song went over all of the common uses of the letter X (marking the spot, standing for danger, railroad crossing signs, poison warnings), described the letter (2 straight lines crossing over in the middle), all via a song by a muppet on a set showing all of these things.
Reflecting back, it was actually a decent educational song about the letter X. It did mention the word xylophone as an afterthought at the end of the song, but it was less kitchy than, say, a song entirely about xylophones or x-rays or what have you. Frankly, this song kind of cemented my opinion as a kid that the letter X was really cool, and to this day I still like the letter X.
And now that I've written this blog entry, hopefully the earworm of the aforementioned song will eXit (pun intended) my head and leave my thoughts clear for the next couple of days/letters.