Mormons love to put their beliefs on public display. One Mormon running into another is like running into your
long lost brother. Therefore,
Mormons will often display their religious affiliation in signs. Signs also set off a perceptive person's
modar (like
gaydar except for Mormons).
One such sign is the RULDS2? bumper sticker or license plate frame. RULDS2? of course means "Are You Latter Day Saint Too?" Latter Day Saint is a contraction for the full name of the Mormon's church; The Church of Jesus Christ of Latter Day Saints.
The point of shortening the phrase to appear as six charcters is so that it will fit on a license plate. Yet, nobody has this as their license plate (well, maybe one person per state). I guess it is supposed to make you feel clever for shortening an entire question into six characters.