This whole time, we thought it was puked-up green beer. 

God, we love St. Patrick's Day. Just like all holidays (Halloween, New Year's, Cinco de Mayo), the true history behind the celebration has faded from memory, and is now a great excuse to dress up a certain way and get completely thrashed on appropriately themed alcohol.

So in honor of the millions of pints of Guiness that'll be drained today (along with the thousands of bad decisions), get in the fake-Irish-accent-murderin' mood by watching the famous Chicago River get dyed its famous green hue. 

And who the hell does this every year? The Butler and Rowan family clans are responsible for turning the water bright green, and they've done it for more than 50 years.

The only way to become part of the six-person boat crew is to be related by blood or marriage to either Mike Butler or Tom Rowan, according to The Chicago Tribune.  Each year, the crew shakes an orange powder — a top secret recipe — into the Chicago River from a sifter and it stays green for about five hours.

And since you're gonna pound a Guiness shortly, here are some facts to impress your drunk friends with. 

On a typical day, Americans drink about 600,000 pints of the Dublin-based beer. But on St. Patrick's Day, about 3 million pints of Guinness are downed, according to Guinness in an email to USA TODAY Network.