Jiu-Jitsu, Bubble Wrap, and Yoo-Hoo - S1-E17
Plot hole: Near the start we see Sheldon using physics to try and take down Tam. This completely goes against all of Sheldon's phobias about touching people, especially socks. Even before this episode he has shown his displeasure at the thought of touching people. (00:05:00)
Answer: Some people just have a dislike for someone that can't be explained. Could be as simple as the way he's dressed.