Brown Fishing 

Brown Fishing is where men (usually gay men) send other men pictures of there shit to gauge their reaction to see if they are game

Tom went brown fishing with multiple men in the hope of finding a companion who liked it dirty

Brown Fishing by The raver May 21, 2019

Fishing for brown trout 

Anal sex

I wanted to try something new and my girlfriend said try fishing for brown Trout

Fishing for brown trout by Anonymous September 5, 2003

Fishing for brown trout 

Lifeguard slang for seiving turds out of a swimming pool. This is usually done after clearing the pool, followed by a 1 hour break from pool use while you 'shock' the pool (i.e. dump a ton of chemicals into it and the run the filters at full blast).

I had to go fishing for brown trout today during the 'mother and baby' swim lessons. At least I got paid for an hour of playing computer games while the filters did their thing.

Fishing for brown trout by JG El Supremo February 15, 2020

fishing for boneless brown trout 

to take a shit, or numerous shits

My stomach hurts so I'm gonna go fishing for some boneless brown trout.

fishing for boneless brown trout by The dude May 1, 2003