SNL’s lead-in last night was Charlie Sheen’s ustream webcast that aired at 10 PM, EST. However, if you tuned in around 9:50 PM because you were nervous you weren’t going to get a spot (the internet can’t be THAT big, right?), you would have seen a closeup on a corner in one of Sheen’s rooms and you would have heard lots of distinct noises of flatulence (recorded ones, but still). On what exactly happened when I started things, nobody is really sure. Charlie took some ideas from the late night talk shows, and adorned his table with an index card that…