Charles Earle Funk’s book, “A Hog on Ice & Other Curious Expressions,” attributes the expression to royalty or other dignitaries being mounted on the heavy charger horses used in battle or tournaments. The term was first recorded in the fourteenth century, and referred to a person selecting a large horse for a pageant as evidence of their high rank. The expression remains, and means someone is pretentiously and arrogantly demonstrating superiority.