I feel for you, Penelope, having spent most of my youth with types singing at me, each thinking himself a sterling wit.
But how can you boycott Marks & Sparks - how can you do without their cosy little black jersey skirts, their delicious purple sprouting broccoli, their hummous, their chicken stock in a jar, their salmon mousse, their handy big pots of herbs that you can plant in the garden?
Boycott Amazon instead - the HSUS (equivalent to Britain's RSPCA) has a court case going for some years to stop them selling goods related to cockfighting and dogfighting.