Cheese whacking is something that only can be by men who are well endowed. It entails removing one's penis and smacking it on a solid surface - normally a table. A really good cheese whack will not only make a half decent noise it will also leave a knobcheese
stain on the surface in question.
Cheese whacking can have several meanings. Normally it means "look at my cock, isn't it big". However, it can also take the form of abusing an inanimate object, such as a computer.
Tom got really angry with the server, so he cheese whacked it.