Irish Waterfall 

An Irish Waterfall is whilst smoking you inhale the smoke and then open your mouth, whilst doing this the smoke will rise up out of your mouth. As the smoke is rising out you inhale back through your nose which will the take the smoke from your mouth back into you throat and lungs recycling it.
Snoop Dogg is seen quite often hittin an Irish Waterfall.
Its hard to execute and when its done right its of tha hook!

"yo hit an Irish Waterfall for me homey!"
or
"Sweet Irish Waterfall!"

Irish Waterfall by Dan-Hulk October 22, 2006

Irish Waterfall (Irish fish market, Luck of the Irish, Drunken Irishman) 

It's when a guy takes a full beer (preferably Guinness) and empties it in a womans vagina during intercourse. The man then proceeds to drink the alcohol from the opening as it flows out in similarity to a waterfall.

An Irishman is having sex with a lady, and decides to pour his beer right down her vagina in order for him to go drink, and lick it out while pleasuring his companion. This is then called an Irish Waterfall (Irish fish market, Luck of the Irish, Drunken Irishman).

Irish Waterfall (Irish fish market, Luck of the Irish, Drunken Irishman) by GregoryLarkinRonan March 18, 2010

The Irish Waterfall

When you take out a person's glass eye and shoot your load in the empty socket creating a waterfall of cum from her nose and mouth

"Yo dude, we got drunk last night and picked up this gross bitch who had a glass eye. Ryan thought it would be funny to give her The Irish Waterfall, so he did. It was solid!!"

"Craig has an infatuation with The Irish Waterfall, I think his boyfriend likes it!!"

The Irish Waterfall by DartmouthInDaHouse September 3, 2009