Make sure if you get a shared workload that it is obviously split between the two of you, your boss should be saying'you do this lot and you do this lot' that way when the other dude does feck all it'll immediately show up. If your boss isnt assigning work to individuals then do exactly half the work and dont mention the rest to anyone, after a couple of days it'll soon be noticed and you'll both get called in and asked to explain yourselves. This is the point at which you get the KY out and fist the other dude royal
SPUD