A fork of Rural Dictionary
To poke the bottom of one's shirt (preferably a button up) through the zip in the your trousers. This created a weiner type effect, but with the material of your shirt as opposed to an actual penis. To obtain an erection like effect do the zip up all the way to the top, trapping the shirt. This will make it stand up.
Callum made the funniest trouser weiner on the bus today! It was 6 inches high!