Occurs when you are extremely constipated to the point where you have to insert a finger into your compacted rectum and "fish" out the turds. Usually results in a bloody finger/turd.
Man, last night I was so constipated and the stool softener wasn't doing the job so I had to go turd fishing.
Turd fishing is when the water level in a toilet is very high; or a man's penis is recovering from a hard-on and is still semi-erect and the end of his penis is submerged like fishing bait. Much like fishing but in a toilet so therefore fishing for turds.
"Holy shit man those, toilets are insane I had a nibble from a foot long whopper because I was turd fishing for so long!"