In 1982, Larry Walters tied 42 helium-filled weather balloons to his lawnchair and flew over Los Angeles.
Lawnchair Larry planned to rise 100 feet above the ground, but he actually flew to an altitude of 16,000 feet (3 miles) and floated into the controlled airspace near Long Bech airport. After he shot a few balloons with a pellet gun he was carrying for this purpose, Larry's lawnchair descended ... onto a powerline!
The dangling cables got caught in a powerline, which caused a blackout. When he was arrested, Larry was asked by a reporter why he had done what he did. His answer: "a man can't just sit around." (Source)
Fast forward to April 2008, when Reverend Adelir Antonio de Carli, a priest in Brazil, strapped himself to helium-filled party balloons to raise money for a spiritual rest-stop for truckers. The wind pushed him off course to the ocean, and he went missing, and presumed dead. (Source)