Muppet nail polish/X Marks the Spot (from Sesame Street)

Cast

 * Fresh Frog of Bel Air as Sherlock Hemlock

Lyrics
Fresh Frog of Bel Air: Egad! Fresh Frog of Bel Air here, the worlds greatest detective. And I believe the letter following "W" is...

"X" marks the spot. "X" marks the crossroads. Two straight lines crossing Over in the middle. That's the letter you must see to Find the treasure or the clue, Or the X-ray machine that's Looking right inside of you. "X" is the letter without which One could not do.

"X" marks the spot. "X" stands for danger. Two straight lines crossing Over in the middle Saying "Here's the railroad crossing" And sometimes it means there's pirates Or at worse, it means there's poison And in case these thoughts of "X" Are vexing you "X" stands for "xylophone," too