Some background information about myself: I am generally a life-before-work kind of person, and tend to mind my own business in the workplace. However, I will socialise with colleagues, if the chance presents itself. I am also interested in staying fit and have been playing golf on and off for most of my life. I don't really have a handicap, and just play for fun.
A number of years ago, I played nine holes of match play with a colleague, who was determined to beat me, and was convinced he could, because he'd taken lessons with the local pro. After beating him 4 up with 3 to play, he resorted to calling me a cheat, saying I gave myself a better lie in the rough. I didn't, because I didn't have to, and even if I had, I still would have beaten him. Afterward, he was constantly frosty around me, and never offered to play golf with me again. He made me feel like his shortcomings were my fault.
Currently, the office knows I love golf, and the boss wants to go for a round with me. The trouble is, he stinks. He showed me a video of his swing; it looks like an octopus making love to a sailboat in a force 10 storm. I am worried he is going to turn on me after the round. I can't make up excuses like "oh, I'm resting this weekend", or similar, because he knows I play regularly, and he knows enough to know that me hitting a 7 iron off the tee on a par 5 to give him a chance is patronising.
What should I do? Should I change my job? I thought about making up a story about my clubs being stolen, but he keeps mentioning playing together. I don't think I can talk my way out of the match. I'm not at all good at my job, and I fear he will try to humiliate me in front of my colleagues.
EDIT: Thank you all for the useful answers. I will emphasise to the boss that we are playing against the course, rather than each other. I will also allow him to decide his own handicap (providing he doesn't officially have one). Regarding my job: I am in a junior position and still learning the trade. Nothing relating to my attitude should be inferred.
EDIT 2: Changing my spelling, by americanising it, is very patronising.