The state your balls are in after not having been washed for a week (or two), especially if one has masturbated often. The result is a rank, fish-like smell rising from your nether regions.
Dude, I have whacked it so much this past week, and now I have to shower. I have a total fish basket going on right now.
Quite simply, male masturbation.
"Aw man, I was picking apples for such a long time last night. I thought my wrist was going to bend backwards."