Cleaning out the fish-tank 

A particularly large dose of man fat applied liberally to the inside of a woman's beef curtains. Ideally needs to be enough for a fair amount of drippage

Jon : Why didnt you answer your phone last night?

Ad : Mate! I was cleaning out the fish-tank

Jon : but i phoned back an hour later

Ad : Bow chicka wow wow

Cleaning out the fish-tank by ExcellCRW November 27, 2011

cleaning the fish tank 

A slang term for lesbians eating each other out.

What were u girls doing in there? Cleaning the fish tank.

cleaning the fish tank by Slam Clown January 20, 2010

cleaning the fish tank 

v. : to engage in sexual intercourse or other sexual activities in the bathroom.

Andrew: Dude, what was that girl and guy doing in the bathroom?
Leo: They were just cleaning the fish tank.
Henry: "Cleaning the fish tank"

cleaning the fish tank by scoobydrew February 26, 2008

Water the Fish Tank 

To put water into one of the huge Brita pitchers.

Running low on the water, time to water the fish tank!

Water the Fish Tank by thatthugnamedtom February 9, 2010

The 55 Gallon Fish Tank 

When you muff dive into a woman that is made of at least 55% body fat and come back out for air smelling like Nemo's abusive alcoholic uncle.

Hey Steve, you douchebag, after I took her out to a nice dinner at Popeye's we went back to her trailer where I gave her The 55 Gallon Fish Tank. Four showers later and I still can't wash her mush off my moustache. Overall, it was a great date with your sister. Asshole.

The 55 Gallon Fish Tank by Larry and Rex and Benny July 8, 2018

hitting the fishtank 

It is slang for smoking weed, pot, marijuana. It came from a group of guys wondering if you could use a fish tank as a bong and get the fish high.

I was hitting the fishtank a little to hard last night and passed out.

weed getting high

hitting the fishtank by Teej September 24, 2016