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)
Freshman Orientation and the Inventor of the Zipper - S4-E6
Plot hole: Memaw gets a call from Dr. Sturgis saying that he has moved to Waxahatchie and would she please call him back. He does not say the new phone number, and this was well before cell phones were in widespread use by the general public, so it could only be a land line. Memaw calls him back, although she could not know the number.
Answer: Some people just have a dislike for someone that can't be explained. Could be as simple as the way he's dressed.