A former colleague, who had been a dons fan, switched in his mid-teens to c****c because he was "fed-up watching them lose".
One Saturday evening, he came in without a coat in the depths of winter to show off his garish new away top and gloat about the doing Celtic had given us that day (I think this was during the Ebbe period). Fortunately, he had to hang up his top and change into his KP jacket, allowing me to soak it thoroughly and hang it neatly on a hanger in the walk in freezer until he finished, 5-6 hours later. He brought it through to the bar, in actual tears, and it was rigid.
The moral of the story is: f**k Celtic.