But "google" is pretty normal, right? Or "yahoo?" Or "bing?"
Your point is well-taken, but I think it's just a matter of normalizing the name. Granted, "duck, duck, go" doesn't roll off the tongue as smoothly as the other services, but I'm not sure that's a critical issue.
I think you've made it clearer for me: the fact that it feels like a sentence plays a big part in the weird factor, it's like I'm addressing someone instead of citing a name for a service.
But I guess it's a minor concern indeed. I just wouldn't feel very confident using a similar name for a product of my own, knowing that it could be a turn-off.
Your point is well-taken, but I think it's just a matter of normalizing the name. Granted, "duck, duck, go" doesn't roll off the tongue as smoothly as the other services, but I'm not sure that's a critical issue.