The problem with the 'wit' ending is that you've got the very gentle "dim" and then it's on to "f-ck" with nothing in between. "Head" as an ending gives you a greater range of nuanced abuse. You can even add it to slang names for drugs as well as swear words - crackhead smackhead to make it socially acceptable in polite company. I highly recommend it.
heading to sydney for the game this weekend and will probably spend Friday and Saturday in a pub so I'll try this out.