What does this nike shirt mean?

Have you ever heard of or seen the monster truck ads saying "Sunday! Sunday! Sunday!"? Wellllll, its making a reference to those, haha. It's still used in some monster truck advertisements, but its also the subject of a lot of parodies. I think the shirts aiming for the humorous side. You should buy it(:

Every airport today has a unique three-letter identifier to streamline the process of tracking the millions of items of airport data transmitted daily, including flight plans and weather reports. Before the 1930s, existing airports used a two-letter abbreviation based on the weather station at the airports. So, at that time, LA served as the designation for Los Angeles International Airport. But, with the rapid growth in the aviation industry, the designations expanded to three letters, and LA became LAX. The letter X does not otherwise have any specific meaning in this identifier.

Looks like it's talking about some sort of car race. Nothing offensive. It could be a reference to the way that monster truck rally announcers say the day of the week.

People used to say Sunday Sunday Sunday when there were monster truck races or derbees.

A far as I know it's just a thing announcers say sometimes.

http://www.youtube.com/watch?v=jDYzidMqq4o

http://www.youtube.com/watch?v=ohp_nmI_TFA (start at 0:30)