"Doug Sanders was on fire through the first two rounds of the 1966 Pensacola Open. He shot 63 in the first round and a 67 in the second, opening up a 4 shot lead. Unfortunately, his hot play garnered a lot of attention, and a throng of fans sought his autograph after the second round. Sanders couldn’t pass up this celebrity, so he spent quite some time signing dozens of autographs. Unfortunately, he forgot to sign his name where is mattered most: on his scorecard. He was thus disqualified from the tournament, losing out on the $10,000 prize and another $25,000 in bonuses from the companies endorsing him."
Ouch. That's was an expensive lesson.