This book is a collection of post-its and messages left by often frustrated people to those that they live with. Often they are quickly scribbled out without thought of the consequences. I lick my cheese is saying "I am fed up always being the one to buy the cheese only for other people to use it. Therefore I am licking my cheese to shame and revolt you but also make myself appear mean and nasty at the same time whilst tarring everybody with the same brush and not allowing for an honest mistake or surpise from the offender that you deem your cheese more important than their friendship. " Other interpretations are available.
Whether you think it is funny or whether you are inspired to ever more cutting and sarcastic notes yourself is a personality thing. clearly some people have reached breaking point, so read it and hopefully become more tolerant as burying them under the patio is never a practical solution in the long run.