when one has been slapped in the face with any number of items, be it an actual trout, a sponge, a banana peel, an anvil, a boobie, whatever. after the slap to the face has occured, the attacker must shout at their victim: "You've been TROUTED!" or simply "Trouted!!" This is not a strict definition, so the rules for usage are not solid.
If you get swindled or taken by someone when somebody fools you into thinking that you've gotten the deal when they come out on top does when you leave the deal with less than what you had you have been traded and if you're doing it you're trouting