To walk around with your dick hanging out, as if to use it to trawl for something.
After sniffing a can of gas, I realized I was trawling.
To trawl, the act or art of trawling.
The pub or bar is about to shut, you havent picked up yet so you "trawl" the room to see what girls are still availible. Sometimes you might have to do some deepsea trawling and might end up with a shocker, it all relates to how strong your beer goggles are.