It's kind of like the Loch Ness monster. Maybe there's something there, maybe there isn't, we'll probably never know. But sometimes it's fun to creep yourself out thinking about it!
[frustrated with everyone about his mother not doing what he wants, after they volunteer to take her to go around Hollywood] What do I say? I say you need to stop ruining my mom's visit, with your [Leonard's] sushi, your [Raj's] sadness, and your [Penny's] slutty shirts. Stop it! [leaves to go to his room]