This episode is a forgotten gem from Season 2, but is one of my favorite early Seinfeld episodes. Jason Alexander (as usual) does a superb job as George in this episode, epitomizing the extreme awkwardness of George's situations that would be re-visited many times in Larry David's Curb Your Enthusiasm.
Jerry and George's chemistry together dominate the episode as they plot to replace an embarrassing message left by George on his girlfriend's answering machine tape. Elaine and Kramer receive very little screentime, but even that doesn't detract from this great episode. Like many Seinfeld episodes, the grand plan of one of the characters (in this case, George) comes to an end in an unexpected manner, but this episode actually had things work out for George in the end, which is something that wouldn't be seen very often afterwards as the series progressed.
All in all, this is another classic not to be missed. In my opinion, the bit about George's father "wearing sneakers in the pool" ranks among the best Seinfeld lines ever.