More clever than anticipated then.
The atomic bomb of pranks - don't know if you can get it in the UK but in the good ol 'US of A, they sell catfish "stink" bait in tubes like toothpaste. For its proper use, you squirt it into fishing lures and the catfish are attracted by the smell - which is utterly horrible. Rotting chicken, cheese and the favorite, blood + cheese.
For it's prank application, squirt it into fine crevices at your office mate's desk, car, home, bed, desk - wherever. Within a day the smell will be unbearable and he'll never find the source of the smell - he'll want to move homes.
It is the atomic bomb so use judiciously. More of a tool of last resort.
KBB-T Blood Tube. 4.5 oz. hangable tube. A proven formula that catches catfish! Powerful blood aroma leaves scent trail in water.
KCBL-T Chicken Liver Tube. 4.5 oz. hangable tube. A special blended formula which is great for catfishing. This robust flavor leaves an aroma as it is trailed through the water.
KBCW-T Catalpa Worm Tube. 4.5 oz. hangable tube. Great bait with a proven track record! Made from the Catalpa Worm, long recognized as one of the best catfish baits. Catalpa Worm Baits...nature's recipe for catfish.
KBRS-T Rotten Shad Tube. 4.5 oz. hangable tube. Shad is a proven fish catching scent. Now we added it to our already great Little Stinker tubes! Even includes fish like scales in the bait for extra attraction!
Cheap too - $3.99 per tube.