Check the cup carefully next time.
Verses from the book of Mormon are printed on them.
Snopes says it is bible verses.
http://www.snopes.com/business/alliance/inandout.asp
Other sites say from the book of Mormon.
Burger and cheeseburger wrappers
Revelation 3:20"Behold, I stand at the door, and knock: if any man hear My voice, and open the door, I will come in to him, and will sup with him, and he with Me."[19]
Beverage cups and antenna toppers
John 3:16"For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life."
Milkshake cups
Proverbs 3:5"Trust in the Lord with all thine heart; and lean not unto thine own understanding."
Double-Double wrapper
Nahum 1:7"The LORD is good, a strong hold in the day of trouble; and he knoweth them that trust in him."[20]
Paper water cups, or "R-9's"
John 14:6 "Jesus answered, 'I am the way, the truth, and the life. No one cometh unto the Father but by Me."