I think the term "magnet ass" dates back to World War II, when airmen whose planes were frequently hit or shot down by the enemy were labeled as such (here's one example). There's a modern variation on the theme, too.
Wirecutter put up a blog post about someone who was hit by lightning three times - and after his death, his gravestone was hit by lightning as well. He might be considered a "magnet ass" for lightning, I suppose. However, that pales into insignificance behind the man who was struck no less than seven times - and possibly an eighth, but because he couldn't prove beyond doubt that it happened, he didn't claim it. Wikipedia reports:
Roy Cleveland Sullivan (February 7, 1912 – September 28, 1983) was a United States park ranger in Shenandoah National Park in Virginia. Between 1942 and 1977, Sullivan was hit by lightning on seven different occasions and survived all of them. For this reason, he gained a nickname "Human Lightning Conductor" or "Human Lightning Rod". Sullivan is recognized by Guinness World Records as the person struck by lightning more recorded times than any other human being.
. . .
He was avoided by people later in life because of their fear of being hit by lightning, and this saddened him. He once recalled "For instance, I was walking with the Chief Ranger one day when lightning struck way off (in the distance). The Chief said, 'I'll see you later'."
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All seven strikes were documented by the superintendent of Shenandoah National Park, R. Taylor Hoskins, and were verified by doctors. Sullivan himself recalled that the first time he was struck by lightning was not in 1942 but much earlier. When he was a child, he was helping his father to cut wheat in a field, when a thunderbolt struck the blade of his scythe without injuring him. But because he could not prove the fact later, he never claimed it.
Sullivan's wife was also struck once, when a storm suddenly arrived as she was out hanging clothes in their back yard. Her husband was helping her at the time, but escaped unharmed.
There's more at the link, including details of the seven strikes Sullivan survived.
Y'know, by about the third or fourth strike I'd have considered changing locations - or my religion!