This is demonstrated in both the unaired, original pilot, and the revised pilot that filmed and aired later. First, from the unaired pilot. This one isn’t as reliable, because the characters have changed since then, but it’s worth including just to see how different things could have gone:
Receptionist: Can I help you?
Leonard: Yes. Um, is this the High IQ sperm bank?
Receptionist: If you have to ask, maybe you shouldn’t be here.
Sheldon: I think this is the place.
Receptionist: Fill these out.
Leonard: Thank you. We’ll be right back.
Receptionist: Oh, take your time. I’ll just finish my crossword puzzle. Oh wait.
(They sit and begin to fill in forms).
Sheldon: Leonard, I don’t think I can do this.
Leonard: What, are you kidding? You’re a semi-pro.
I’m confused as to how the actual aired pilot begins, because it’s been edited down in the reruns, and I don’t want to pay to watch it again on itunes. I watched it when it first aired, but at that point I didn’t know I needed to be on the lookout for evidence of Sheldon’s sexuality! (this is clearly a very important task that I am endeavoring to complete) The actual pilot either begins with the above scene, or begins where this scene would have left off, with Sheldon and Leonard returning to the apartment after a failed trip to the sperm bank. We know this because of this convo:
Penny: So, what do you guys do for fun around here?
Sheldon: Well, today we tried masturbating for money.
Finally, I forgot to include this quote in my prior post about why I think Sheldon would enjoy coitus:
Amy: Let’s look at this logically. I have a stomach, I get hungry. I have genitals, I have the potential for sexual arousal.
Sheldon: A cross we all must bear. You know, in difficult moments like this, I often turn to a force greater than myself.
Amy: Religion?
Sheldon: Star Trek. Did you see Star Trek: The Motion Picture?
Amy: No.
Sheldon: Don’t. It’s terrible. However, in it, we learn that when Spock finds himself drawn off the path of logic by feelings bubbling up from his human half, he suppresses them using the Vulcan mental discipline of Kolinar.
Based on these quotes, I think we can say 3 things for sure:
1. Sheldon does get aroused
2. He has, at least in the past, self-satisfied
3. I need a hobby besides tracking fictional characters’ solo session potential