Is he attracted to me?

The fact that he pokes you in the side or touches you at all (other than hand shakes) is a big giveaway that he likes you. Maybe he is too shy to ask you out also. He also might hesitate to date you because you are colleague at his workplace (many people do hesitate). As far as asking you if you have a boyfriend is clear that he has certainly considered dating you. But then again, he might hesitate as mentioned above. The fact that he has a pet name for you is obvious he is flirting with you.

To give a coworker a pet name or to poke her in the side by surprise is not professional and he probably knows that. So he would only behave that way if he wants more than just a professional relationship. Try asking him for a "casual" lunch (if he's to shy to do it) and see where the lunch conversation takes the both of you.

All sign seems to point out that he likes you. You might however, ask him if he has a boyfriend. I can not explain the acting cold thing but go for it.

Yes, he likes you. Yes, you should make your feelings clear. Go for it.

It does feel good to feel like a goofy teenager once in while, especially about a guy/girl thing, doesn't it :)
I definetly think he is into you. Buy as daddy said, at work it's pretty hard to ask a woman out, at least in most workplaces.
I don't think it would hurt to invite him for lunch or something, outside of work. He and also you will be more comfortable outside.

I think he does like you for sure. At work place, most people want to socialize and be friendly, however some harmless pranks and a little touching always mean something. It's a bit tough since you are at a workplace, and in my opinion, it's harder for men to open to a woman about how they feel at work.
I think you should very vaguely show him that you are interested, maybe a coffe somewhere close to work so you both are not at work while talking, would be a nice place to actually talk about dating or getting a phone number.

I love that feeling!! The butterflies, the anticipation :) He totally likes you, I think. Make sure that when you guys start talking about relationships and such that you and he can keep the lines separate at work. Think of examples or statements you can make to ease any of his concerns (and yours) regarding the risk of dating a co-worker. That may help move things along (?)

I think he definitely likes you! Do you guys have happy hours? Can you ask him if he wants to go with you to the next one or to a friend's happy hour? Grabbing a drink right after work is a casual, no pressure scene to get to know your feelings for each other.