When the fishing is really slow....

For a good laugh when fishing is slow and your mates attention is elsewhere, pull up his line by hand and attach the hooks into the pull tabs of a couple of empty cans {only works if he has a sinker tho' but esp good with a dropper rig or flashers} then send em back down without creating any unwanted attention. Then tell him he just got a bite. The cans do good circles esp with a bit of current and your mate will genuinely think he's got something so you can rag him about it for years to come