Not that anyone really cares, but 10 years ago (June 4, 2003) was the Sammy Sosa corked bat incident. My how time flies.
Here are some more details from Chris Jaffe at Hardball Times:
The league also confiscated all 76 of his bats to test them for cork, but they all came back clean. The five bats he’d previously donated to Cooperstown also were tested and came back clean. Sosa said corking was something he’d just done recently in an attempt to get out of his post-HBP slump, and the evidence backs him up. Despite that, some wondered if Sosa had done this before anyway and if could’ve helped him amass his big homer totals. However, there’s a dirty little secret about bat corking. Of all the methods to cheat, it’s by far the least effective. It’s the placebo pill of the under-handed world. The effects of corking a bat have been studied several times by scientists. It’s even been on an episode of Myth Busters. The results always come back the same: it doesn’t help the ball move forward. If anything, it actually hurts efforts to make a ball go a greater distance.